The two girls are so alike that strangers find __________ difficult to tell one from the other.
| A．it | B．them |
| C．her | D．that |
_______ more to be pitied than blamed．
| A．Uneducated are | B．Uneducated is |
| C．The uneducated are | D．The uneducated is |
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 |