1 . She ________ the letter since two hours ago.

A．wrote

B．has been writing

C．is writing

D．will write

2 . The boy has been ________ (站) out of the door for over an hour.

4 . 自从2个月前，我们就已经在线学习了。
________________

5 . —I called you last night at 9:30 and I believed you ________ be at home because no one answered the phone.
—Sorry, I ________ at that time.

A．mustn’t; would have been sleeping	B．couldn’t; should have slept
C．couldn’t; must have been sleeping	D．might not; need have been slept

6 . 这个婴儿整个早上都在哭。
The baby ________ ________ ________ the whole morning.

7 . 虽然警察已经寻找了那个失踪的婴儿两个星期了，但是至今还没有找到他。
________ the policemen ________ ________ ________ the missing baby for two weeks, they still cannot find him.

9 . 现在她已经做这件事好几年了。
She ________________ this ________________ a few years now.

10 . 现在她已经做这件事好几年了。
She _________ _________ _________ this _________ a few years now.