Question

I personally think__more listening, speaking, reading and writing is the key to__our English. ...

I personally think__more listening, speaking, reading and writing is the key to__our English. A．Doing; improve B．To do; improve C．Do; improving D．Doing; improving

Answer 1

D

think后是宾语 从句，且缺少主语，the key to中 to是介词，后面要跟doing形式，而C项Do不能作主语，所以选D。