原因状语从句是表示原因或理由的，引导这类从句的最常用的连词是because, since, as , now that（既然）等，for 表示因果关系时（它引导的不是从句）为并列连词，语气不如because强。
I didn’t go abroad with her because I couldn’t afford it.
Don’t scamp your work because you are pressed for time.
I wonder whether his hearing is okay _______________ he has turned the television up very loud.
A.unless B. although
C.until D. because
As I didn’t know the way，I asked a policeman. 我不认识路，因而问警察。
As it is snowing, we shall not climb the mountain. 由于在下雪，我们不去爬山了。
1.___________ you weren’t there, I left a message.
A.As B.When C.Though D.For
2.When my father goes somewhere, he always goes along with my mother,_____________ he doesn’t like going alone.
A.though B.as C.while D.even if
Since traveling by air is much faster, they decided to take a plane.
Since you won’t help me，I’ll ask someone else.你既然不帮我，那我就请别人帮忙。
Mark needs to learn Chinese ________his company is opening a branch in Beijing.
A.unless B. until C. although D. since
【解析】考查状语从句的连接词。his company is opening a branch in Beijing是学习汉语的原因。unless除非；until直到……为止；although尽管；since由于，自从。在句中since是“由于”的意思。句意：马克需要学习汉语，因为他的公司要在北京开分公司。
Now(that) you’ve passed your test you can drive on your own.你既已考试合格，就可以独自开车了。
I do remember，now (that) you mention it. 你这一提，我倒的确想起来了。
________the term has come to an end, I am going to take a trip for relaxation.
A.Now that B. Even if
C.As though D. So that
Seeing (that) the weather is bad，we’ll stay at home.天气不好，我们还是呆在家里吧。
Advertisement is distinguished from other forms of communication in that the advertiser pays for the message to be delivered. 广告不同于其他交际形式，因为登广告的人要为其所提供的信息付费。
I’m in a slightly awkward position, in that he’s not arriving until 10th.
The Chinese language ________Western languages ________, instead of an alphabet, it uses characters which stand for ideas, objects or ideas.
A.differs from; in which B. is different from; in that
C.differs from; in what D. is different from; in where
【解析】考查动词短语和连词。表示“与……不同”可以用differ from…或be different from…；in that是固定连词，引导原因状语从句，表示“由于，因为”，故选B项。
1.Perhaps it was_____________ my father often published his poems in the newspapers that he became known through his literary works.
A.before B.when C. if D. because
2._____________fewer people send letters to one another, the number of people collecting stamps has been steadily in decline.
A.Before B.Although C.As D. If
3.Why not stay at home _____________the road is so slippery after the heavy snow?
A.since that B.now that C. then that D. after that
4.________ you have got a job, you should learn to be independent of your parents.
A.So B.Although C. Before D. Now that
5.The old man asked Lucy to move to another chair _____________he wanted to sit next to his wife.
A.although B.unless C. because D. if
6._____________ I can never persuade you to give up buying stocks(股票), I can only wish you good luck.
A.When B.For C.Since D.Although
7.The play has remained a mystery____________ the producer wants to surprise the audience.
A.although B.because C.unless D.until
8.Mary felt sad over the loss of photos she had shot in Australia,___________ that was a memory she especially treasured.
A.as B.which C.when D.where
9.Enjoy the first hour of the day. This is very important___________ it sets the mood for the rest of the day.
A.as B.if C.when D.where
10.I won’t attend the party to be held in Mary’s home,____________ I won’t stay where I feel I’m not welcomed.
A.now that B.so that
Diets have changed in China — and so too has its top crop. Since 2011,the country ___1___（grow）more corn than rice. Corn production has jumped nearly 125 percent over ___2___ past 25 years, while rice has increased only 7 percent.
A taste for meat is ___3___ (actual) behind the change: An important part of its corn is used to feed chickens, pigs, and cattle. Another reason for corn’s rise: The government encourages farmers to grow corn instead of rice ___4___ (improve) water quality. Corn uses less water ___5___ rice and creates less fertilizer(化肥) runoff. This switch has decreased ___6___ (pollute) in the country’s major lakes and reservoirs and made drinking water safer for people.
According to the World Bank, China accounts for about 30 percent of total ___7___ (globe)fertilizer consumption. The Chinese Ministry of Agriculture finds that between 2005—when the government ___8___ (start) a soil-testing program ___9___ gives specific fertilizer recommendations to farmers – and 2011, fertilizer use dropped by 7.7 million tons. That prevented the emission(排放) of 51.8 million tons of carbon dioxide. China’s approach to protecting its environment while ___10___ (feed) its citizens “offers useful lessons for agriculture and food policymakers worldwide.” says the bank’s Juergen Voegele.
1.(2017·新课标卷II改编)The damage is usually more serious on the first plant,but the neighbors, relatively speaking, stay safer __________ they heard the alarm and knew what to do.
A.though B. unless
A.before D. because
2.（2016·北京卷·单项填空）I really enjoy listening to music _______________ it helps me relax and takes my mind away from other cares of the day.
A.because B. before
A.unless D. until