28. I will never know what was on his mind at the time, nor will________.
The problem referred to at the meeting, if___________in time , will have a bad effect on the environment.
In those hard days , we could not leave behind___________came to us for help.
Do you know how much time and effort they devoted___________such a complicated project ?
The government has___________a series of policies and measures to ensure the improvement in living standards.
—Did you read the book Who Stole My Cheese ?—Yes. I___________it twice while in university.