题目内容
7.By the time he was fifteen years old,he advanced maths all by himself.( )A. | had learned | B. | have learned | C. | learned | D. | would learn |
分析 到他15岁时为止,他已经自学了高等数学.
解答 答案是A.本题考查过去完成时;题干中by the time到…时候为止,往往与完成时连用,从句中是过去时,表示到过去某一时间为止,故主句中用过去完成时,故选A.
点评 对时态的选择,要在把握时态的基本用法的基础上,根据具体语境和题干中的时间推断时态,同时关注特殊的结构.
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