___students will take part in the sports meeting and _____them is over three hundred.

Make sure that the machine is kept where it is not ____ to children.

Liu Huan, a famous male singer, has long hair, because he ______ long hair.

Travelling, talking with friends and relatives, and other forms of relaxation are very likely to _______ the well-being of metal health.

____________ jumped into the freezing river to rescuethe drowning girl deserved to be praised.