Question

Edison was a clever boy, and ______ he was fourteen, he had learned advance mathematics by himself.

A．whenever

B．by the time

C．the moment

D．ever since

Answer 1

Ｂ

考察時態(tài)。By the time到…時為止；根據(jù)he had learned advance mathematics by himself中的過去完成時，可知所選擇的連詞是與完成時連用的，結合句意可知Ｂ正確。句意：愛迪生是一個聰明的孩子。到他１４歲的時候，他已經(jīng)自學了高等數(shù)學。