—I beg your pardon?—Your mind must have been when I was speaking, wasn’t it?
Do remember to remind her_________the gas before she leaves.
Last summer holiday, I went back to my hometown, ________ the neighbours and the house ________ I used to be familiar with were gone.
Nuclear science should be developed to benefit the people ______ harm them.
—May I smoke here? —If you ________, choose a seat in the smoking section.
If you want to catch the first bus you’d better ________ for the bus station immediately.