He is so busy with the research _____ he has no time left for any other activity.

We may find that learning a foreign language does not have to be________learning our mother tongue，but can in fact be twice ________

was in clas on Fridayafternoon, but no one has seen her since—She _____ an accident

Are you free______ weekends Shall we go to the cinema,OK

Though having discussed it for long, they still haven’t reached an agreement they should pour more money into the project.