The harmful effects that smog can have on people's health are one of the top ______ of those who live in some cities.
A.concerns B.conflicts
C.characters D.charges
You’d better communicate with each other sincerely, and I hope to see your conflict ________ tomorrow.
A.was to be solved B.has been solved
C.will have been solved D.had been solved
1 have one regret about the time I spent in high school: I _______ more advanced classes that are really helpful in college.
A.couldn't have taken B.should have taken
C.needn't have taken D.must have taken
It wasn't until I ______ took part in the activity that I understood the meaning of it.
A.actively B.personally
C.rarely D.normally
My skating teacher was really great and ______ I knew it, I was able to skate!
A.before B.since
C.until D.after
Robert went to Shanghai in his 20s, ______ several years later, he became a manager.
A.when B.where
C.which D.who
