The river has become much ______ than before because of the waste water from the factories.
A. dirty B. dirtier C. Dirtiest
.Many people didn’t realize the importance of health _______they have fallen ill.
| A．until | B．while | C．when | D．after |
---Let’s go to Kunming for vocation. It’s _________too hot ________too cold there.
| A．either; or | B．neither; nor |
| C．not only; but also | D．both; and |
----Do you know Robert?
----Yes, He is ________ university student. He likes sports and runs for ___________ hour every morning.
| A．a; a | B．a; an | C．an; an | D．an; a |
Thank you for me to join you.
| A．invite | B．invited | C．inviting | D．invites |
Math is not easy, I like it very much.
| A．so | B．but | C．if | D．or |