They_____the train until it disappeared in the distance.

下列各句中，没有语病的一句是（ ）

Obviously, the boss looks happy again, doesn’t he—Yes. It’s said that he has ______ the difficult problem.

It was a matter of________ would take the position.

As the family did not make a(n) _____ ahead oftime, they had to wait at the restaurant in order to get a table.