题目内容


Although the causes of cancer ____we do not yet have any practical way to prevent it.
A．are being uncoveredB．have been uncovering
C．are uncoveringD．have uncovered
A
考查被动语态。选项A是现在进行时的被动；选项B是现在完成进行时的主动语态；选项C是现在进行时的主动语态；选项D是现在完成时的主动语态。根据题意：虽然癌症的成因长在被揭示，但我们眼下还没有防止它的实用方法。故答案为A.
练习册系列答案
相关题目
Don’t worry. I’ll         in my home for a week.
A．stay you upB．put you upC．put up youD．put you away
—Joan，what ________ in your hand?
—Look！It's a birthday gift for my grandma.
A．had you heldB．are you holding
C．do you holdD．will you hold
With more forests being destroyed, huge quantities of good earth ______ each year.
A．is washing awayB．is being washed away
C．are washing awayD．are being washed away
— ________ for the glass! —It’s OK. I’m wearing shoes.
A．Look outB．Walk out
C．Go outD．get out

一Ready to give up guessing，Sandy?
一No，no，hold on! I think I______ at the answer now．
A．arriveB．am arrivingC．have arrivedD．will arrive
—What happened? I called you several times yesterday evening, but I couldn't get through.
—Sorry, my sister and I ________ on the phone all the time.
A．talkedB．have talked
C．were talkingD．have been talking
—Guess what，we've got our visas for a short－term visit to the UK this summer.
—How nice！You ________ a different culture then.
A．will be experiencingB．have experienced
C．have been experiencingD．will have experienced
In the last few years thousands of films ____ all over the world.
A．have producedB．have been produced
C．are producingD．are being produced

违法和不良信息举报电话：027-86699610 举报邮箱：58377363@163.com

精英家教网