In order to find out how the famous painting was stolen as soon as possible, more experienced policemen have been sent to _____ the case.

It is well known that good relationship between twocountries_____ the development of mutual culture and economy.

This article is difficult for me. Could you please explain it to me—I’m afraid I have to say sorry, but the book is _________ my understanding.

Mr Smith together with his two children ________ early every morning.

Five people won the “China’s Green Figure” award, a title ______ to ordinary people for their contributionsto environmental protection.