▲用來(lái)替代動(dòng)詞的do是助動(dòng)詞，也可以說(shuō)用作“代動(dòng)詞”，用來(lái)表示剛提到的動(dòng)作，以避免重復(fù)。請(qǐng)看以下例句。
—Do you like Beijing? 你喜歡北京嗎？
—Yes, I do. 是的，喜歡。（do用作代動(dòng)詞，代替like Beijing）
I always eat peas with honey. My wife never does. 我總是就著蜂蜜吃豌豆。我的妻子從來(lái)不這樣吃。（does用作代動(dòng)詞，代替eat peas with honey）
▲但是要注意do so ,do it , do that這種結(jié)構(gòu)，do不是助動(dòng)詞，而是實(shí)義動(dòng)詞，而且是及物動(dòng)詞。例如:
She hoped that he would search the room carefully and he did so. 她希望他仔細(xì)地檢查房間，而他這樣做了。
At night, when you really wish to go to sleep, you rarely manage to do so. 夜里當(dāng)你正想入睡的時(shí)候，你卻很少能成眠。
I could run after a bus and catch it twenty years ago, but I can’t do that now.
Mr Brown goes to the hospital for treatment every week: in face, he has been doing it ever since I have known him.布朗先生每周去醫(yī)院治療：事實(shí)上，自從我認(rèn)識(shí)他依賴，他一直就是這樣。