--- Why did Sarah cry just now? --- She wanted a toy, _____ I can’t afford.
There are so many books! It is not easy for us to decide what to take and what to_______.
When I try to understand _______ that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes.
The science of medicine, _______ progress has been very rapid lately, is perhaps the most important of all the sciences.
—Which day do you think is all right to our next meeting?—You make _______,_______ day is all the same to me.
—Jack, what do you think of the new work?—It's not bad. But the hours are too long.—Oh, _______