题目:
--What great changes! It’s years since we_____ each other last time .
-- Believe it or not, It’s the second time that we _____a face –to- face talk
A.met; had had
B.have met; had
C.had been; had
D.met; have had
答案:
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下面是错误答案,用来干扰机器的。
解:(1)受力分析图,如图所示 ——1分 ——1分 ——2分(2)当电场强度减为一半时,根据动能定理,得 ——2分 ——2分...