求数值孔径为1.5的显微镜的正常放大率．（设瞳孔直径为3.0mm．)

A. I am sad.

B. I am feeling well.

C. I am dirty.

D. I am very tired.

Why did the farmer say to the doctor "Here I am again"？

Because he wanted to make the doctor believe that he was not ______.

I don' t believe such a strange story. I am certain it is a complete______.

A．fabrication

B．lubrication

C．synthesis

D．generalization

Which of the following is closest in meaning with the sentence: "I am feeling black"？

A．I am sad.

B．I am feeling well.

C．I am dirty.

D．I am very tired.

The sentence "I am sorry" belongs to

A．commissives.

B．directives.

C．representatives.

D．expressives.

A、I am sorry I have to run off.

B、I'm glad to be your friend.

C、I am so lucky

D、I'm snowed under.

听力原文：Why did the farmer say to the doctor "Here I am again"？

Why did the farmer say to the doctor "Here I am again"？

Because he wanted to make the doctor believe that he was not ______.

I am not of those people who like a strenuous(费力的)holiday; I believe in______.

A．took it easy

B．taken it easy

C．taking it easy

D．taking it easily