The car must have been doing at least 100 miles an hour.

　　這車速肯定每小時(shí)至少100英里。

　　Biological systems have been doing this for billions of years

　　生物系統(tǒng)億萬(wàn)年來(lái)一直都是這樣。

　　Some scientists have been doing research on artificial internal organs.

　　一些科學(xué)家一直在研究人造內(nèi)臟。

　　What have you been doing this week?

　　你這個(gè)星期都在做些什么？

　　What have you been doing with yourselves?

　　你們這一向是怎么過的？