diff --git a/1000-hours/sounds-of-american-english/1.2-phonemes.md b/1000-hours/sounds-of-american-english/1.2-phonemes.md
index 999869e1..e39c3a54 100644
--- a/1000-hours/sounds-of-american-english/1.2-phonemes.md
+++ b/1000-hours/sounds-of-american-english/1.2-phonemes.md
@@ -19,6 +19,24 @@ Vowels can be classified into *long* and *short* vowels, or alternatively, they
 | Short vowels | `ʌ`, `e`, `ə`, `ɪ`, `ʊ`, `ɒ`      |                                                |
 | Long vowels  | `ɑː`, `æ`, `əː`, `iː`, `uː`, `ɔː` | `aɪ`, `eɪ`, `ɔɪ`, `aʊ`, `oʊ`, `eə`, `ɪə`, `ʊə` |
 
+6 个基础元音中，`ə` 和 `ɪ` 有相对更多的变体（*allophone*）：
+In the 6 basic vowels, `ə` and `ɪ` have relatively more variants, or *allophones*:
+
+* `ɪ`：
+  * 除了长元音版本 `iː` 之外，还有一个半长版本 `i`，例如 *happy* `/ˈhæp·i/`[^1]；
+  * In addition to the long vowel version `i`ː, there's also a semi-long version `i`, as in *happy* `/ˈhæp·i/`.
+* `ə`：
+  * 长元音版本 `əː` 在 CEPD[^2] 中被标注为 `ɜː`，例如 *bird* `/bɜːd/` (UK)
+  * The long vowel version `əː` is annotated as `ɜː` in the CEPD[^2], like in *bird* `/bɜːd/` (UK).
+  * 儿化的短元音 `ə` 被标注为 `ɚ`，例如 *mother* `/ˈmʌð·ɚ/`；
+  * The rhotacized short vowel `ə` is annotated as `ɚ`, as in *mother* pronounced `/ˈmʌð·ɚ/`.
+  * 儿化的长元音 `əː` 被标注为 `ɝː` 例如 *bird* `/bɝːd/` (US)
+  * The rhotacized long vowel `əː` is annotated as `ɝː`, like in *bird* pronounced `/bɝːd/` (US).
+
+另外，英式英语中还有两个三元音: `aɪə` 比如，*fire* `/faɪə/`；*hour* `/aʊə/`。在英式英语中，这两个三元音被简化为两个双元音的更为明显的儿化音，`aɪə` → `aɪr`，比如，*fire* `/faɪr/`, *hour* `/aʊr/`。
+
+Furthermore, in British English, there are two triphthongs: `aɪə` as in *fire* pronounced `/faɪə/` and `aʊə` as in *hour* pronounced `/aʊə/`. In American English, these two triphthongs simplify into more apparent rhotacized diphthongs, `aɪə` → `aɪr`, for example, *fire* pronounced `/faɪr/`, and *hour* pronounced `/aʊr/`.
+
 ## 1.2.2 辅音（Consonants）
 
 英文大约 28 个辅音。
@@ -36,3 +54,10 @@ English approximately has 28 *consonants*.
 | Nasal     | Voiced        | `m`, `n`, `ŋ`           |
 | Lateral   | Voiced        | `l`                     |
 | Semivowel |               | `j`, `w`                |
+
+辅音 `t` 在美式英语中有个弹舌音变体，`t̬`，例如，*cutting* `/ˈkʌt̬·ɪŋ/`。
+
+The consonant `t` has a flapping variant, `t̬`, as in the word *cutting*, pronounced `/ˈkʌt̬·ɪŋ/`.
+
+[^1]: The middle dot `·` in `/ˈhæp·i/` is an annotation of syllable division. A dot `.` is used in CEPD, but for clearer html rendering, we use a raised one here.
+[^2]: CEPD, Cambridge English Pronunciation Dictionary, https://dictionary.cambridge.org/help/phonetics.html.
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