diff --git a/1000-hours/sounds-of-american-english/3.2.6-sz.md b/1000-hours/sounds-of-american-english/3.2.6-sz.md
index 83734b8e..ce289042 100644
--- a/1000-hours/sounds-of-american-english/3.2.6-sz.md
+++ b/1000-hours/sounds-of-american-english/3.2.6-sz.md
@@ -5,3 +5,12 @@
 The `s/z` sounds don't really pose a challenge for most people. When producing these sounds, the tip of the tongue is close to, but not touching, the *seam* between teeth and gums.
 
 ==此处需要图片==
+
+需要注意的是，`s` 之后的 `p`、`t`、`tr`、`k` 会被浊化，相应读成 `b`、`d`、`dr`、`g`：
+
+It's important to note that following an `s`, `p/t/tr/k` are voiced, meaning they are pronounced like `b/d/dr/g` respectively.
+
+> * *speak* `/spiːk/` → `/sbiːk/`
+> * *student* `/ˈstudənt/` → `/ˈsdudənt/`
+> * *school* `/skuːl/` → `/sguːl/`
+> * *frustrate* `/ˈfrʌˌstreɪt/` → `/ˈfrʌˌsdreɪt/`
diff --git a/1000-hours/sounds-of-american-english/3.3.2-stress.md b/1000-hours/sounds-of-american-english/3.3.2-stress.md
index b12fdfa6..c9a33912 100644
--- a/1000-hours/sounds-of-american-english/3.3.2-stress.md
+++ b/1000-hours/sounds-of-american-english/3.3.2-stress.md
@@ -21,7 +21,7 @@ What Asian learners of English must be especially mindful of is to mentally corr
 The word *individual* `/ˌɪndəˈvɪdʒəwəl/` has a total of *5* syllables, which is equivalent to the length of *5* Chinese characters. Consider the comparison between the number of syllables in the following sentences
 
 > * 人们看法各不相同。`[Rénmen kànfǎ gè bù xiāngtóng]` —— 总计 *8* 个字，*8* 个音节。
-> * 人们看法各不相同。`[Rénmen kànfǎ gè bù xiāngtóng]` - *8 characters in Chinese, 8 syllables*. 
+> * 人们看法各不相同。`[Rénmen kànfǎ gè bù xiāngtóng]` - *8 characters in Chinese, 8 syllables*.
 > * People's opinions vary from individual to individual. `/ˈpipəlz əˈpɪnjənz ˈvɛri frəm ˌɪndəˈvɪdʒəwəl tə ˌɪndəˈvɪdʒəwəl/` —— 总计 *7* 个单词，*19* 个音节。
 > * People's opinions vary from individual to individual. `/ˈpipəlz əˈpɪnjənz ˈvɛri frəm ˌɪndəˈvɪdʒəwəl tə ˌɪndəˈvɪdʒəwəl/` - *7* words in English, *19* syllables.
 
@@ -54,4 +54,3 @@ In English, in addition to primary stress, secondary stress, and unstressed syll
 Let's dig deep into the word *individual*, for example, it's pronounced as `/ˌɪndəˈvɪdʒəwəl/`. If each syllable was placed equal stress, it would sound something like /ɪn-dɪ-vɪ-dʒju-əl/... Within this pronunciation, the vowel `ɪ` in the second syllable `/dɪ/` is reduced to the schwa sound, `ə`; likewise, the vowel `ju` in the fourth syllable `/dʒju/` is also reduced to `ə`, but retains the coloration of `u`. The `l` at the end of the syllable, which originally carries a slight `ə` sound, thus becomes a very light `wᵊl`...
 
 ![5-syllables-individual](/images/5-syllables-individual.svg)
-
diff --git a/1000-hours/sounds-of-american-english/3.4.3-cc.md b/1000-hours/sounds-of-american-english/3.4.3-cc.md
index 406cd2e8..b3f075e8 100644
--- a/1000-hours/sounds-of-american-english/3.4.3-cc.md
+++ b/1000-hours/sounds-of-american-english/3.4.3-cc.md
@@ -1,2 +1,76 @@
 # 3.4.3. 辅音 + 辅音（Consonant + Consonant）
 
+“**辅音 + 辅音**” 的组合需要注意的地方相对较多。
+
+The combination of "consonant + consonant" often requires more attention.
+
+## 3.4.3.1 省音（elision）
+
+“**辅音 + 辅音**” 的组合，常常会造成前一个辅音虽然发声器官（*articulator*）动作完整但并不发声的情况，于是会出现一个既 “看不见” 也 “听不到” 的**停顿**（*stop*，[3.4.1](3.4.1-stop)），之前举过单词内存在这种情况的例子，*hotdog* 和 *network*，再比如，*hard-nosed*, *partner*…… 
+
+A "consonant + consonant" combination often results in an instance where the first consonant is articulated but not voiced, creating an *invisible and inaudible stop* (3.4.1). Examples of this within words include previously mentioned *hotdog* and *network*, as well as *hard-nosed*, *partner*, and so on.
+
+有人把这种现象叫做 **省音**（*elision*）；但，这种说法容易产生误导，因为音的确是省了，但，动作却没省，不仅没有省，**动作还很完整**。
+
+Some refer to this phenomenon as *elision*. While it's true that the sound is dropped, the action of articulation isn't skipped – in fact, it's fully completed.
+
+在意群中，更是经常出现前一个词汇末尾是辅音，后一个词汇开头也是辅音的情况 —— 同样会出现**省音**。
+
+Within a meaning group, it's common for a word to end with a consonant and the following word to begin with one, resulting in *elision*.
+
+## 3.4.3.2. 叠音（geminates）
+
+上一个音节末尾的辅音和下一个音节开头的辅音相同的时候，这一对相同的辅音被称作**叠音**（*geminates*）。在连贯的自然语音中，这两个辅音就只发声一次 —— 但听起来的时候，有可能感受到前一个辅音存在造成细微停顿。它从机制上来看，其实和**省音**（[3.4.3.1]()）一样。其实哪怕相邻的两个辅音相似的时候，也会发生同样的现象。
+
+When the same consonant ends one syllable and begins the next, this pair of identical consonants is known as **geminates**. In fluid, natural speech, these two consonants are vocalized only once— yet, you might sense a slight *stop* due to the presence of the previous consonant, and its completion of articulating action. Mechanically, this is similar to **elision** (3.4.3.1). This phenomenon also occurs even when two neighboring consonants are just similar, not identical.
+
+比如，*at that time*, 不是 `/ət ðæt taɪm/`，而是 `/ə·ðæt̬aɪm/` —— 第一个 `t` 由于后面跟着一个辅音，于是产生了**省音**，听不到了，但，该有的停顿却依然在，在这里我们用 `·` 代表那个停顿 ；而后，第二个 `t` 与第三个 `t` 是**叠音**，这两个 `t` 只发声一次。又比如，*a bad day*, 不是 `/ə bæd deɪ/`，而是 `/ə bæ·deɪ/`。 再比如，*with this*, 不是 `/wɪθ ðɪs/`，而是 `/wɪ·ðɪs/`。
+
+For instance, *at that time* is not pronounced as `/ət ðæt taɪm/`, but as `/ə·ðætaɪm/`. Here, the first `t` is elided because it is followed by another consonant, so you can't hear it. However, the expected pause is still there, represented by `·`. Then, the second `t` and the third `t` form a geminate, and are vocalized only once. Similarly, *a bad day* is not pronounced as `/ə bæd deɪ/`, but as `/ə bæ deɪ/`; *with this*, is not `/wɪθ ðɪs/`，but `/wɪ·ðɪs/`.
+
+## 3.4.3.3. 同化（assimilation）
+
+同化（*assimilation*）主要有两种情况：
+
+Assimilation, in English pronunciation, primarily happens in two key scenarios:
+
+> * `t` + `j` = `tʃ`
+> * `d` + `j` = `dʒ`
+
+最常见的比如，*Don't you?* `/dəʊn tʃju?/`；以及，*Would you?* `/wʊ dʒju?/` 这里的关键在于，`t, d` 发声时起始的舌尖位置如果放对了（[2.2.4](https://1000h.org/sounds-of-english/16-tdsz.html)），它与后面的 `/ju/` 连起来的发声就只能如此。
+
+For example, in daily conversation, we often hear *Don't you?* pronounced as `/dəʊn tʃju?/`; and *Would you?* as `/wʊ dʒju?/`. The key here lies in the position of the tongue tip when pronouncing `t, d`. If placed correctly (as explained in [2.2.4](https://1000h.org/sounds-of-english/16-tdsz.html)), it naturally leads to such pronunciation when followed by `/ju/`.
+
+同化主要发生在 `j` 这个音上。除了已经讲过的 `j` 前面遇到 `t` 和 `d` 时会产生同化之外，
+
+Assimilation mainly happens when a word ends in `j`. Besides the explained cases where `t` and `d` are followed by `j`,
+
+> * `s` + `j` = `ʃ`
+> * `z` + `j` = `ʒ`
+
+比如，`s+j` 可能会被读成 `ʃ`，`z+j` 可能会被读成 `ʒ`。再比如，*Miss you so much.* `/mɪ ʃu səʊ mʌʧ./`；*It was your job.* `/ɪt wɒ ʒʊr ʤɒb./`
+
+For instance, the combination `s+j` might be pronounced as `ʃ`, and `z+j` might be pronounced as `ʒ`. Here are examples: *Miss you so much* can be pronounced as `/mɪ ʃu səʊ mʌʧ./`; *It was your job* can be pronounced as `/ɪt wɒ ʒʊr ʤɒb./`
+
+请注意，这两组是**可能**，并非一定，并非所有英文母语使用者都如此发音。
+
+However, it's important to note that these are possibilities, not certainties. Not all English native speakers pronounce words this way.
+
+## 3.4.3.4. 击穿（dropping）
+
+“辅音 + 辅音” 的组合中，如果第二个辅音是 `h` 的话，它常常被击穿（*dropping*），因为 `h` 原本就是很轻的音，发音时声带并不震动，所以总是自然而然地被前后发音相对更为响亮的声音所掩盖。
+
+In a "consonant + consonant" combination, where the second is `h`, the `h` sound often gets *dropped*, simply due to its soft nature. This is because the *vocal cords* don't vibrate when pronouncing `h`, and it naturally gets overshadowed by the louder sounds before and after.
+
+比如，*Was he hurt?* 三个单词分开读，应该是 `/wɒz hi həːt/` 在连贯的语音中，会被读成 `/wɒzi həːt/` —— 听不到 `h`，它被击穿了。
+
+For example, take the sentence *Was he hurt?* If pronounced separately, it should be `/wɒz hi həːt/`. However, when spoken fluidly, it sounds more like `/wɒzi həːt/`; the `h` becomes unnoticeable.
+
+很多美国人在 `t` 这个音上还有另外一个特殊的习惯，`t` 跟在 `n` 之后的时候，美国人说话的方式会让我们听不到那个 `t`，也就是说，`t` 也可能被击穿。比如，他们说 *interview* 的时候你听到的可能是 `/ˈɪnəˌvju/`，没有 `t`。
+
+Many Americans have a unique habit with the `t` sound, especially when it follows `n`. Their way of speaking often causes the `t` to disappear. For instance, when they say the word *interview*, you might hear `/ˈɪnəˌvju/`, without the `t`.
+
+另外，`ð` 也可能被击穿，基本只发生在 *them* 这个常用词上。比如，*let them* `/lɛt ðəm/`, 变成了 `/lɛt-əm/`，由由于 `ð` 被击穿了之后，`t` 等于被夹在了两个元音之间，于是会变成浊化的弹舌音 `t̬`，于是，说出来的或者听到的是 `/lɛt̬əm/`…… 所以，在自然语流中 *let him* 和 *let them* 实际上没有任何区别，需要通过上下文确定究竟是 *him* 还是 *them*。
+
+In addition, the `ð` sound can also be dropped, primarily in the common word *them*. For example, *let them* `/lɛt ðəm/` might become `/lɛt-əm/`. When the `ð` is dropped, the `t` ends up sandwiched between two vowels and turns into the voiced flap `t̬`. So, what you say or hear becomes `/lɛt̬əm/`. Therefore, in natural speech, *let him* and *let them* sound identical and only context can determine whether it's *him* or *them*.
+
diff --git a/1000-hours/sounds-of-american-english/3.4.4-vv.md b/1000-hours/sounds-of-american-english/3.4.4-vv.md
index e69de29b..c2c911a1 100644
--- a/1000-hours/sounds-of-american-english/3.4.4-vv.md
+++ b/1000-hours/sounds-of-american-english/3.4.4-vv.md
@@ -0,0 +1,24 @@
+# 3.4.4. 元音 + 元音（Vowel + Vowel）
+
+“元音 + 元音” 的组合之中，会出现**加音**（*intrusion*）。
+
+In combinations of "vowel + vowel", an *intrusion* sound may occur.
+
+前一个元音以 `ɪ/i/iː` 结尾，会出现加音 `j`：
+
+When the first vowel ends in `ɪ/i/iː`, an intrusive `j` sound emerges:
+
+> - *I am* - `/ˈaɪ ˈæm/` ⭢ `/ˈaɪjæm/`
+> - *He is* - `/ˈhiː ˈɪz/` ⭢ `/ˈhiːjɪz/`.
+> - *She is* - `/ˈʃiː ˈɪz/` ⭢ `/ˈʃiːjɪz/`.
+> - *They are* - `/ˈðeɪ ˈɑːr/` ⭢ `/ˈðeɪjɑːr/`.
+
+前一个音节以 `ʊ` 结尾，比如 `ʊ/uː/aʊ/əʊ`，会出现加音 `w`：
+
+Similarly, when the preceding syllable ends in `ʊ`, such as `ʊ/uː/aʊ/əʊ`, an intrusive `w` sound appears:
+
+> - *Go away* - `/ˈɡəʊ əˈweɪ/` ⭢ `/ˈɡəʊwəˈweɪ/`
+> - *Do all* - `/ˈduː ˈɔːl/` ⭢ `/ˈduːwɔːl/`
+> - *Do it* - `/ˈduː ˈɪt/` ⭢ `/ˈduːwɪt/`
+> - *Throw it* - `/ˈθrəʊ ˈɪt/` ⭢ `/ˈθrəʊwɪt/`
+