1.------the best student in his class,he felt very happy.
A.Considered B.Considering C.Having considered D.To consider
2.-Is Charlie sick?-Yes,-----------all right in the rain causes him --------a cold
A.To work,catching B.To have worked,catching
C.His working,to catch D.Having worked,caught
3.He said that he much regretted --------to help us on that matter
A.being not able B.not being able C.not to be able D.to be not able
请详细解答。谢谢

1.A.Considered， 被认为，余答案无此意。
2.C.His working,to catch， 冒雨干活用动名词且时态上和问句相衔接，故选His working；cause sb.to do sth 为惯用句型。故选to catch。
3.B.not being able，regret doing sth. 为惯用句型且否定形式为：regret not doing sth.故不选ACD。