A number of tests have been conducted to _______ that these drugs have no side effects.

Annie used to ____ with her parents, but now she is used to _____ with her classmates at school.

I have no idea ______ measures the government will take to stop the air from being further polluted

The tourists, had enjoyed themselves so much in the botanic garden, were worn out

car requires _____, Jeff.–Sure. You know it is also what I want to have _____ for long.