Although he knew little about the large amount of work done in the field , he succeeded ____other more well-informed experimenters failed.
Tom’s English is not good, so he devoted all his free time to __________ it.
Who will be ___________ the company when the manager (经理) is out?
________ is a very popular sport in summer.
John failed in the exam, ________he had prepared a lot for it before.
—______ have you studied English? —For six years.