As there is less coal and oil, scientists are exploring new ways of making use of _____ energy, such as sunlight, wind, and water for power and fuel.
| A．primary | B．alternative | C．instant | D．unique |
Earth is believed ______ by an object the size of Mars at some point in the distant past
before its surface cooled．
| A．to be hit | B．to have hit | C．to have been hit | D．to hit |
With temperature ______ so rapidly, we could not go with the experiment．
| A．fall | B．falling | C．fallen | D．to fall |
--- Is John in the office?
---I didn’t see ______ there．
| A．anyone | B．someone | C．everyone | D．each one |
Because of ______high demand for Type AB blood，____supplies of it are usually limited．
| A．the；the | B．不填；不填 | C．不填；the | D．a；the |
His parents never approve of_____ he plans to do, which always annoys him．
| A．whatever | B．no matter what | C．no matter when | D．whenever |