Scientists are convinced ________ the positive effect of laughter ________ physical and mental health

We had a really bad time about six months ago but now things are ________．[ ]

Miss Smith is a friend of ______

Tom hid himself behind the door, _________ he could hear the steps of his mother clearly.

Don’t be angry with your kid when he makes a mistake again, will you —No. I won’t. I know that ______of us are perfect after all.