一个高为8分米的圆柱形水桶里，装了半桶水．把水倒出12升后，剩下的水恰好占水桶容积的20%．这个水桶的底面积是多少平方分米？

补全对话，每空一词。

—Excuse me, Mr. Green, where are you __1__?

—I'm from London. That's in __2__.

—Oh, great! Where do you __3__ now?

—I work in shanghai.

—__4__ do you do?

—I'm a __5__. I drive a bus. 

— How many children do you have?

—I have one.

—Do you have a son __6__ a daughter?

—I have a son.-What __7__ he do?

—He's a student. He __8__  in No. 4 Middle School.

—How __9__ is he?

— He's fifteen. Do you have any children?

—Yes. I have a daughter. She's a student, too. She __10__ English very much.