Keep yourself open we can experience the great joy that friendship can bring.

Scientists are convinced ________ the positive effectof laughter ________ physical and mental health

Be _____we can’ t expect an absolute freedom of expression.

下列各句中，加点的成语使用不恰当的一句是（3分）

What do you think of being a volunteer, John?—I find it a stressful job but one ___ you can really help people.