You never know how much difficulty we had _______ the problem .Luckily, we managedto solve it with Mr Zhang’s help.
Helen________her keys in the office so she had to wait until her husband________home.
The pen I________I________is on my desk.
________got into the room________the telephone rang.
Tom was disappointed because most of the guests________when he________at the party.
—Why did you miss the English class? —Because my alarm clock didn’t________.