?? 詞語組成解析
john
[[d??n]]
n. 盥洗室, 廁所, 嫖客
霍爾丹(姓氏)
??? 情景例句
I keep in touch with my family regularly.
我定期和家里保持聯系。
Do you have a letter of introduction?
你有介紹信嗎？
a wave length (the horizontal distance between two wave crests),
波長（兩個浪峰間的水平距離）