The doctors are doing all that they _____, but the old man is still not breathing properly.

He tried his best to solve the problem, _____ difficult it was

_____ the fans are waiting for the popularsinger outside the concert hall.

See? Only ten dollars for such a nice tie?——OK,_____

1 like this set of sofa so much, but I don’t know ______ to put it in my small house. —You’re supposed to put it in the living room.