第35题: [单项选择]Mrs. White became a teacher in 1985. She ______ for twenty years by next summer. A. will teach B. will have taught C. has been teaching D. will have been taught 参考答案:B 答案解析:[考点] 将来完成时
[句意] 怀特夫人从1985年就开始当老师,到明年夏天就整整20年了。
[解析] by+时间一般与完成时连用,接表示将来的时间就用将来完成时,接表示过去的时间就用过去完成时。