It is reported that in our country cities __________ heavy air pollution that is 30 percent above the national standard or higher should try to meet standards by 2030.
If you leave the club, you will not be ________back in.
Mr. Alexander doesn’t just write for fun; ______, writing is his bread and butter.
I don’t believe that he will marry Kathy whom he doesn’t love at all,________?
Rather than ________ on a crowded bus,he always prefers ________ a bicycle.
I think teachers should be strict _______ their students ______ studies.