How much do you ______ mending a pair of shoes?-Only one dollar, sir.[ ]

Efforts will be made to______ new teaching models to exploit the students’ potential.

Living in the central Australian desert has its problems, _____getting water is not the least.

He’ll never forget his stay in the park ________ he found his cellphone which had gone missing days before.

I think he is taking an active part insocial work .—-I agree with you __________.