Everyone in this country should work hard and do what they can _____ against national smog.
I was disappointed with the film . I had expected ______ to be much better.
Does ______ matter if he can’t finish the job on time?
I don’t think ____ possible to master a foreign language without much memory work.
Is ____ necessary to complete the design before National Day?
I hate _______ when young people speak to the elderly in a rude way.