Why don’t you go out to play, Rose—I’m afraid I can’t. I have much homework _________.

In addition to keeping on taking ________ exercise, Alan is also going on ____ diet to lose weight.

68. The Summer Palace is one of the _____ parks in Beijing. I suggest you going there to have a visit.

We can never expect ________ bluer sky unless we create________ less polluted world.

_____， he often forgot to turn off the lights.