The United States of America___one of the most developed countries in the world.
| A．is | B．are | C．was | D．were |
-- Did you visit your grandparents yesterday?
--Yes, and when I got there, they _____ in the fields .
| A．worked | B．have worked | C．were working | D．had worked |
_____ is known to all is that effective measures should be taken to deal with the problem of the over-exploiting of our resources.
| A．What | B．It | C．As | D．Which |
In Australia, surfing is a popular sport among young people _____ they can seek excitement and adventure.
| A．that | B．which | C．whom | D．where |
The children went home from the grammar school, their lessons _____ for the day.
| A．finishing | B．finished |
| C．had finished | D．had been finished |
Cheating is strictly forbidden in this important exam, and students ______ bring any reference books into their classrooms, cell phones included.
| A．will not | B．should not | C．mustn’t | D．need not |