给下面句子排序。(用数字表示)
①It's a knife.
②What's this in English?
③Excuse me, Wang Bing.
④Thank you.
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读地球公转示意图,回答下列问题
如图所示,小明用羊角锤拔铁钉,请画出在A点施加最小动力F的示意图及其力臂l.