_________ is a growing world problem, and nowadays the United Nations and its member countries _________hard to deal with it.
_____ to go abroad, his spare time is totally spent in learning English.
It was a bit doubtful at first, but it ____ to be a really good idea.
——Alice looks sad. Did you tell her about the accident? ——Yes, but I ______ her just before her final examinations.
With a lot of difficult problems ____, the manager felt a heavy burden taken off his mind.
I suggest you choose _____ you think is kind and friendly.