英语问题。1.We haven't seen each other for almost 20 years,but I recognized her ____ I sawller. A.the moment B.the moment when C.for the moment D.at the moment 2.Is this the reason ____ at the meeting for his carelessness in his work? A.why he explained B.what he explained C.how he explained C.he explained 交际题 3.Excuse me ,is this seat takern? ___. A.Quite sorry B.I am sorry C.Certainly is D.No,I don't think so 我知道第一题的答案A,第二题的答案是D,第三题的答案是D,但不知道其中的原理?请老师帮忙解疑,谢谢了