_______ necessary for us _______ our environment clean and tidy.
| A．This is; keep |
| B．That’s; to keep |
| C．It’s; to keep |
| D．It’s; keep |
She was afraid of __________SARS because it was dangerous.
| A．catch | B．catches |
| C．caught | D．catching |
-----Who taught _________Japanese?
----I learned it by ______________.
| A．you, myself |
| B．your, I |
| C．yourself , me |
| D．yourself, myself |
Humans can’t live _______air.
| A．without | B．with |
| C．in | D．for |
---Oh, you have a headache and a cough. _______have you been like this?
---Three days.
| A．How long | B．How soon |
| C．How often | D．How many |