The river has become much ______ than before because of the waste water.A. dirty B. dirtier C. Dirtiest
Mike has much difficulty ________ Chinese so he often asks me ________ help.
As a policeman , you must yourself and your work.
I decided not to wait any longer ______ I waited for him at the station for two hours.
You’d better ______ others during the night. It’s not polite.
—You look so happy . Any good news ?—Yes . ________ I walked out of our school , I met an old friend .