If it__________ for the joint efforts made by the whole nation, we couldn't have contained the coronavirus in such a short time.
A.hadn't been. B.shouldn’t have been. C.hasn't been. D.wouldn't be.
To improve learning efficiency, students must spend more time focusing on the skills__________ they are weak in.
A.what B.where C.when D.which
I know I was___________ , so I will apologize to Sara today.
A.at risk. B.at fault. C.at ease. D.at random.
I have resigned, and they have a free hand to appoint__________ they like in my place.
A.whenever B.however C.whatever D.whomever
This part of the book isn't very interesting, so I'm going to_________ it.
A.deny B.cancel C.skip D.digest
He flashed me a quick smile but rapidly swallowed it___________ he saw my expression.
A.when. B.unless. C.if D.until
