Who’s singing in the next room— It ____ beher . She has gone to New York.

下列各句中，表达得体的一句是

Why are you carrying so many books—I want to find the information about some famous people _____ I can use in my speech.

I’m writing to apologize for my absence from last week’s meeting. I was unexpectedly ________ at work.

Scientists think that there has been lifeon Earth for _______ years.