Please don’t drop litter _______, you should throw it into the dustbin _______.

These are ____ erasers,and _____ are white.

Sam is a very good man. He always tries __________ best to help others.

.—How can I get along _____with others, Dad?—Try to smile to others, boy. That will make ________much easier.

I’m so sorry that you didn’t win the skating marathon.－How long _____ you ______?－I skated for 5 hours.