The stretches of mountains are the natural _____ between the two countries.
| A．position | B．barrier |
| C．regulation | D．approach |
I prefer ___ to ___.
| A．do; talk | B．doing; talking | C．do; talking | D．doing; talk |
I’ll go to bed as soon as my homework______.
| A．do | B．does | C．are done | D．is done |
Which do you like, the former or the ___.
| A．late | B．later | C．latter | D．latest |
They will arrive there ___ next month.
| A．any time | B．some time | C．sometime | D．sometimes |
___ is ____
| A．Seeing… believing | B．Seeing…to believe | C．To see…believing | D．To see…believe |