______I went to the USA, I visited many cities.[ ]

Scientists say it may be five or six years _____ it is possible to test this medicine to human patients

How much do you know about the 3D film technology?—A little. Not until _______the hot movie Avatar _______ some about it.

Why does your brother ________ a sad look on his face these days?

It was said that _____ was the reason why he didn’t attend the meeting.