Scientists say it may be five or six years ____ it is possible to test this medicine on human patients.A.before B.after C.since D.when这种before 和when还有after老搞不清楚,怎么区别选择?答案不是B,C额，老选不对这类题目

求翻译What do scientists say about the collision of an asteroid with Earth? It is very .What do scientists say about the collision of an asteroid with Earth? It is very unlikely but the danger exists Scientists say it may be a fe years___it is possible to test the new medicine on patients.求翻译、谢谢 say it say it 英语翻译请问,And scientists say it may hold the secret to being fat and happy 中的to being能不能改为to be? Scientists say it may be ten years _____ this medicine was put to use.A since B before C after D.when 给出正确答案,理由和翻译 Scientists say it may be five or ten years__it is possible to test this medicine on human patients.A:sinceB:whenC:afterD:before选哪个?为什? Scientists say it may be ten years _____ this medicine was put to use.A since B before C after D.when 给出正确答案,理由和翻译 Scientists say it may be a few years___it is possible to test new medicine on patientsA.because B.after C.before D.since scientists say it may be five or six years____it is possible to test medicine to human paientsA sinceB afterC beforeD when 1.Teens are ______ sleepy to be happy.2.Scientists say school should _____ later.3.Kate eats candy every day,t______ she knows it is bad for her health.4.It's a_____ how to form good habits. 英语翻译Scientists say it may be five or ten years ______ it is possible to test this medicine on human patients.A.since B.before C.after D.when Dinosaurs once lived happily on the earth.But 65 million years ago,they suddenly died out.What happened to them?Some American scientists say it is because there were not e___male dinosaur Many scientists say that it’s important for us to have ______ food in our diet.各选项的意思分别是什么呢?A.a variety of B.a great deal C.a large number of D.a good many Scientists say that the Mars-500 days_______they perform the task during the real mission-Good luck.I hope it goes well.A. after B. before C. since D. as请问为什么?另外,这句话怎么翻译? 英语高中单选The scientists say that new research makes ____possible to turn light into soundA this B that C it D one求解该选什么? 我觉得是C..谁能详细解释下么? 英语翻译1Scientists say that none of the differences is really important.2It doesn’t matter if a person eats dinner at 4 o’clock in the afternoon or at eleven o’clock at night. Boston Habor is so polluted that scientists say it won't recover until the next century____a.at most b at least c.at latest d at best 为何不选择B而要选择D,