题目内容：

they spent as many hours as they could_____their lessons?
A.to study B.studying C.STUDY Dstudied

优质解答

B
考察的是固定句型spend some time (in) doing sth. 这是这句话的主干 as many as they could只是插入、修饰作用 强调花了尽可能多的时间 用could诱惑你选A项