_______ provides many hours of air for astronauts in space.
A. An air tank B. A power pack C. A helmet D. A space sleeping bag
We are wondering ________ we can prevent people from polluting the earth.
A. who B. that C. whether D. what
The gravity on Mars is only about ________ of that on Earth.
A. 1/2 B. 2/3 C. 1/8 D. 3/8
It is hard to imagine what life __________ in 100 years.
A. will like B. will be like C. likes D. might like
My friend John insisted that he had seen ______ alien the day before.
A. a B. an C. some D. any
Our teacher asked us to write a _________ letter in English this morning.
|
A．ninety-word |
B．ninety-words |
|
C．ninety word |
D．ninety words |
