Make a mark _____ you don’t understand.
A.until B.unless C.where D.as
Few people paid full attention to their health conditions _____ they were seriously ill.
A.when B.if C.until D.before
John thinks it won’t be long ______he is ready for his new job .
A.when B.after C.before D.since
_____ he came to study in the university, he has made much progress in the study of English.
A.While B.When C.Since D.After
I had to buy _____ of these books because I didn’t know which one was the best.
A.both B.none C.neither D.all
It is polite _____ you to give your seat to the old man on the bus.
A.for B.to C.of D.about
