先化简后求值：（2a+b）（2a﹣b）+3（a﹣2b）2+（﹣3a）（3a﹣4b），其中a=﹣1，b=﹣2．
解：（2a+b）（2a﹣b）+3（a﹣2b）2+（﹣3a）（3a﹣4b）
=4a2﹣b2+3（a2﹣4ab+4b2）﹣9a2+12ab
=4a2﹣b2+3a2﹣12ab+12b2﹣9a2+12ab
=﹣2a2+11b2，
当a=﹣1，b=﹣2时，
原式=﹣2×（﹣1）2+11×（﹣2）2
=﹣2+44
=42．
| 从方框中选择恰当的句子，补全对话。 Bob: Hi, Bill! I've heard you are a football fan, aren't you? Bill: Yes. Bob: __1__ Bill: Well, when I watch a football game, I feel excited. __2__ Bob: Just a little bit. I'm not good at playing football. __3__ Bill: Oh, I see. Do you have any favourite football stars? Bob: __4__ Bill: Oh, I like him, too. Bob: __5__ Bill: Not much. I'm going to join a football club so that I can play football more. Bob: That's a good idea.
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