单项填空（共20题，每小题1.5分，共30分）
“We can’t go out in this weather,” said Bob, ____ out of the window.
| A．looking | B．to look | C．looked | D．having looked |
---How much salt did you put in the dish?
--- _____.
| A．None | B．Nothing | C．No | D．No one |
It usually takes courage to _____ an invitation.
| A．turn down | B．turn up | C．turn out | D．turn to |
--- The weather is too cold _____ March this year.
--- It was even _____ when I came here years ago.
| A．for; colder | B．in; cold | C．in; hot | D．for; hotter |
He is rather difficult to make friends with, but his friendship, _____, is more true than any other.
| A．once gained | B．when to gain | C．after gaining | D．while gaining |
On rainy days, accidents _____ happen sometimes on steep roads.
| A．should | B．shall | C．must | D．can |