.Not only her mother but slao her fatherin the same school for twenty years.A. will teachB

问题补充：

.Not only her mother but slao her fatherin the same school for twenty years.

A. will teach

B. has taught

C. have taught

D. are teaching

答案：

A. will teach

(答案→)B. has taught

C. have taught

D. are teaching

解析：句意：不仅他的母亲而且他的父亲也在这个相同学校教了了。Not only …. but slao….不仅….而且….结合语境可知用现在完成时现在完成时结构：have+过去分词，现在完成时表示到说话时为止（或到现在为止）已经发生或完成了（不一定结束）的动作或状态。过去某一时间开始并一直持续到现在并且有可能还会持续的动作或状态。故选B。