At a rough estimate, our new campus is ____________ the one at present.
| A．twenty times the size as |
| B．twenty times the size of |
| C．twenty times as the size of |
| D．the size twenty times of |
_____ all my teachers, Mr. Moore is the one who impresses me most.
| A．At | B．On | C．To | D．Of |
Hurry up!The train ______. You know it ______ at 8:30 am.
| A．leaves; leaves | B．is leaving; is leaving | C．leaves; is leaving | D．is leaving; leaves |
In recent days ,with the help of our teacher , I have made ___ great progress in _____mathematics.
| A．a; the | B．/ ;/ | C．/ ; the | D．a ; / |
Mrs. Green always helps her mother even though going to work _________most of her day.
| A．takes out | B．takes down | C．takes up | D．takes off |
We have to admit that the biggest___________ facing the ecosystem is limited resources and the worsening environment.
| A．mission | B．challenge | C．scale | D．contribution |