Historical experience can as a most important source of information.
| A．serve | B．use | C．regard | D．prove |
I find this treatment is very to my health.
| A．willing | B．illegal | C．beneficial | D．serious |
They really had a great time, designing everything, drawing the blueprint, ______the angles and so on.
A looking out B taking out C finding out D figuring out
When a discussion is under way, everyone is welcome to have the_________ in class.
A floor B time C chance D right
—Can you help me with the English homework, mom?
—You can’t always other’s help for your homework. Do it by yourself this time.
| A．wait on | B．rely on | C．insist on | D．turn on |
The bus was held up by the snowstorm, the delay.
| A．causing | B．caused | C．having been caused | D．to cause |