You should go over your test paper ________ you hand it in.— OK, Mr. Wang.

_______ the Atlantic Ocean crosses the equator, the trade winds cause a flow of water to the west.

The professor was so ______, hardly anyone came to class.

The transportation in our country is much more ______than it used to be.—But traveling becomes much easier!

Canthose at the back of the classroom hear me?-No problem.[ ]