He has devoted himself __ mankind.to benefit B. benefiting C. to benefiting D. benefited
The open-air celebration has been put off __________ the bad weather.
__________ fire, all exits must be kept clear.
Some students often listen to music __________ classes to refresh themselves.
— __________ when has the country been open to international trade? — 1978, I suppose.
— I think he is taking an active part in social work. —I agree with you __________.