have has doing是什麼時態

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臟。

It is said the industrial production has been doing well.

據說工業生產一直很好。

China has been doing its bit to act the part.

中國一直在盡力的做它應該做的事情。

He has been doing mass work and engaged in scientific research.

他一直從事羣衆工作和科學科研工作。