Artemisinin (青蒿素) was first________ by Chinese scientist Tu Youyou in the 1970s.
A.invented B.created C.produced D.discovered
— Could you clean up the living room and take out the rubbish, Andrew?
— Of course! Seeing this________, Mom will be mad, I think.
A.difficulty B.matter C.mess D.wonder
Extreme sports such as rock climbing can be very dangerous, so we________ be too careful.
A.can’t B.mustn’t C.shouldn’t D.needn’t
— On March 30, 2020, a forest fire broke out in Sichuan.
— Yes. You can’t believe how terrible the fire is ________you see it with your own eyes.
A.because B.unless C.since D.though
About ________ of the earth is covered with water, but more and more water has been polluted.
A.three-forth B.three-forths C.three-fourth D.three-fourths
I________in London for over ten years, but I’ve never regretted my final decision to move back to China.
A.was living B.would live C.lived D.have lived
