I didn’t understand my parents why they are so strict ______ me ______ my schoolwork.

Must I hand in my homework now， Mr.Smith—No，you ________.

Children won’t put on weight easily if they___ to eat fruit and vegetables

sit in an office all day long and rarely _____,you’re likely to suffer from neck andback pains.

We really shouldn’t use plastic bags any more when shopping.—_____ It’s important to protect our environment.