diff --git a/1000-hours/sounds-of-american-english/2.2.3-td.md b/1000-hours/sounds-of-american-english/2.2.3-td.md
index cb46df39..d12f1d76 100644
--- a/1000-hours/sounds-of-american-english/2.2.3-td.md
+++ b/1000-hours/sounds-of-american-english/2.2.3-td.md
@@ -34,9 +34,13 @@ The t sound may be the most complex in American English
> * Flaping t̬: When t is situated between two vowels, it tends to be flaping t̬, sounding like d, as in water ˈwɑːt̬ɚ.
> * 喉塞音 ʔ - m/n/l 之前的 t 有可能变成喉塞音 ʔ，比如，*utmost* ˈʌʔˌmoʊst, *fitness* ˈfɪʔnəs, *witness* ˈwɪʔnəs, 或 *fruitless* ˈfruːtləs。如果你不知道喉塞音是什么样的，听听 *Uh-Oh!* —— ʌʔoʊ……
> * Glottal Stop ʔ - The t before m/n/l might transform into a glottal stop, as in *utmost* ˈʌʔˌmoʊst, *fitness* ˈfɪʔnəs, *witness* ˈwɪʔnəs, or *fruitless* ˈfruːtləs. If you don't understand what is a *glottal stop*, listen to the phrase, *Uh-Oh!* —— ʌʔoʊ...
-> * 省略音 ᵗ - n 之后的 t 可能会被省略掉，比如，*winter* ˈwɪnᵗər —— 当然，若是读成 ˈwɪntər也没错……
-> * Optional ᵗ - The t following n might be omitted, as in *winter* ˈwɪnᵗər - of course, ˈwɪntəris also correct.
+> * 省略音 ᵗ - n 之后的 t 可能会被省略掉，比如，*winter* ˈwɪnᵗɚ —— 当然，若是读成 ˈwɪntɚ也没错……[^1]
+> * Optional ᵗ - The t following n might be omitted, as in *winter* ˈwɪnᵗɚ - of course, ˈwɪntɚis also correct.[^2]
美式发音中，相对最特殊也需要最多注意和练习的辅音是 t，元音是 ɚ/ɝː（[2.1.5](2.1.5-ə)）。
In American English pronunciation, the consonant t and the vowel sound ɚ/ɝː ([2.1.5](2.1.5-ə)) deserve special attention and practice due to their unique characteristics.
+
+[^1]: *nd* 中的 d 也常常并不发音，最常见的比如 *and* 会被读作 ən，再比如，*a second offer* 会被说成 ə ˈsekən‿ɑːfɚ。
+
+[^2]: In American English, the d in "*nd*" also often goes silent. For example, "*and*" is usually pronounced as ən. Another instance is "*a second offer*," which sounds like ə ˈsekən‿ɑːfɚ.
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