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

　　這車速肯定每小時至少100英里。

　　Biological systems have been doing this for billions of years

　　生物系統(tǒng)億萬年來一直都是這樣。

　　Some scientists have been doing research on artificial internal organs.

　　一些科學家一直在研究人造內(nèi)臟。

　　So, what have you been doing today?

　　那你今天都干什么了？

　　What have you been doing this week?

　　你這個星期都在做些什么？