Such a good opportunity may not come again, so you ____________ let it go this time.

Many teenagers don’t get enough sleep because they have too much homework, which _____ them up at night.[ ]

d worker insisted that he________ old,and________ back to the working post again

_______ the fact that his original experiments had failed, Pro. White stuck to his research.

mmer Palace is really beautiful In fact, Idoubt whether China has _________ park