Studying in groups is necessary _________________ you want to do well in school.

A.if B.until C.unless D.though

Eric arrived on time, _______ it was the rush hour.

A. though    B. because    C. while    D. unless

(2017河北34题)Mom won't let Dick go out ________ he promises to be back by 10：00 tonight.

A.if B.when C.since D.unless

Bob, dinner is ready. Please wash your hands ________ you eat.

A.until B.after C.while D.before

I like dancing, ________ I don't have enough time to practice it.

I didn't know anyone at the party, ________ I felt a bit lonely.

Smile to the world,     the world will smile back to you.

A. or    B. and    C. so    D. but

My arm is still painful,         I'm going to see a doctor.

A.so B.for C.but D.or

Which one would you prefer, tea ________ coffee?

A.but B.or C.and D.so

Go downstairs, ________ stand in line on the playground as soon as possible.

A.and B.but C.so D.or