Usually, we don`t know how important something is _____ we lose it.
A. or B. until C. as soon as
A little boy wrote _____ “u” and _____“n” on the wall.
| A．a; an | B．an; a | C．an; an | D．a; a |
--- Why do you often take exercise? --- _____ me keep fit.
| A．Help | B．Helping | C．To help | D．helped |
--- We went to see the man who was in hospital yesterday. --- __________.
| A．So did we | B．So we did | C．We did so | D．Did so we |
I am thirsty, Could you let me have _____ coke?
| A．little | B．any | C．some | D．other |
If H2 burn in O2, we can get _____.
| A．H2 | B．H2O | C．O2 | D．H2O2 |