__ gas leaks and similar accidentsshould occur, some responsible persons should regularly inspect all thelaboratories

While I was standing ______the window, I saw several boys running _______the street.

It’s convenient to own a car; however,I don’t think it’s good to drive one________you go,especiallyin places with a lot of traffic[ ]

___ you lose the paper document, sign in wwwSina.com, __ you might download all you need

We haven’t dicussed yet _______ we are going to place our new furniture