Don’t____________to tell us if you have a problem.We’re friends,aren’t we?
He worked late into the night yesterday. That’s ___ he couldn't get up on time this morning
--___ today? ---It's sunny.
Don't worry about ___ haven't arrived yet.
It is ___ we depended in Japan.
How long did it take them to get ___ this river? A.through B,over C.across D.till