What are you going to do this weekend?—–I’m going to help _____the city parks with my classmates to make them clean.

_______ for your step, Jim, or you might fall into the lake. – Well, I got it．

Is there anyone here name isBetty? —- Sorry, I don’t know.

We have to finish so much work within two days. We can’t __________ to waste any time.

So little ________ about science that the lecture was my understanding.