________have you visited the Great Wall?-Once.[ ]

May I go out with you tomorrow? —If your job ______by then.

I don’t think fast food is good for our health, so I_______ go to MacDonald.

Where are my keys, Dad? I can’t find them.—- Look! They’re under the table. You must _____.

Where is your mother? She_____________ Shanghai on business for a few days..