It is difficult __________ a best friend.
| A．finding |
| B．found |
| C．to find |
| D．find |
The number of smokers in the countryside is usually greater than _______ in cities.
| A．that | B．those | C．one | D．the one |
Most of us see a doctor ______ when we get a cold or something.This won't cost us a lot.
| A．suddenly | B．immediately | C．occasionally | D．frequently |
May I use your bike? I'm going to see my uncle who _______ this city.
| A．visits | B．will visit | C．has visited | D．is visiting |
It is playing computer games _______ the boy spends most of his spare time.
| A．that | B．which | C．when | D．how |
---What's he size of the smaller one?
---It's _______.
| A．half bigger | B．half as big | C．as half big | D．half the same |