-- Look at the boy running on the ground. Is it David?-- It _______ be him. I saw him go to the teacher’s office just now.

—Must I take much medicine every day?—No, you ________.

The door _____ open, no matter how hard she pushes.

 For everyone’s safety, we ___________ a1ways remember the law against driving after drinking.

It was a fine day yesterday. I ________ have taken my raincoat with me.