The trip _______ us about four hours by plane.
| A．spent | B．paid | C．cost | D．took |
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 |
--- What pleasant weather! Shall we go boating on the lake?
--- _______.
| A．That’s right | B．Thank you very much |
| C．It doesn’t matter | D．Sounds great |