Like other animals, we are          until we know it is safe to relax.

on purpose

on fire

on guard

on duty

考查介词短语辨析。句意：像其他动物一样，我们在知道安全的时候才放松警惕。A.on purpose 故意；B. on fire着火；C.on guard 警惕；D.on duty值班。结合后文we know it is safe to relax，可知我们在知道安全的时候才放松警惕。故选C项。

We cannot           the punctual arrival of trains in foggy weather.

get

help

guarantee

guess

考察动词词义辨析。句意：我们不能保证火车在雾天准时到达。A. get得到，获得；B. help 帮助；C. guarantee保证；D. guess猜测。根据句意可知，火车无法保证按时到达。故选C项。

If you work hard like this, you will           sooner or later.

give out

break up

break down

fall down

考查动词短语。句意：如果你继续这样辛苦工作的话，你迟早垮掉。A.give out分发 ；B.break up打碎；C.break down垮掉；D.fall down 跌倒。根据句意可知break down符合语境。故选C项。

There                   in the world              China is a great country with a long history and rich culture.

are no doubt; that 

are not doubts; if

is no doubt; that

is not doubt; if

考查固定句型和同位语从句。句意：毫无疑问，中国是世界上有着悠久历史，丰富文化的一个大国。分析句子可知，这个句型为 there is no doubt that 引导，表示“毫无疑问......”.本句为that that 引导的同位语从句，句意和句子结构完整。故选C项。

One of the man holds the view          the book said was right.

that

whether

what that 

that what

考查同位语从句及主语从句。句意：其中一个人认为这本书说的是对的。分析句子可知，the view后面接了一个同位语从句（     the book said was right.），从句句子成分齐全，应使用that 引导，连接词在从句中不做成分，无意义。在同位语从句中又有一个主语从句（     the book said），在主语从句中said 缺少宾语，应用what 引导，指代“......的（事情，东西）”。故选D项。

He          and wept when he heard the news.

took down

put down

turned down

broke down

考查动词短语辨析。句意：当他听到这个消息时，整个人都崩溃了并哭起来。A. took down  记下；B.put down记下；C.turned down调小，拒绝；D.broke down崩溃，坏掉。根据wept 可知此处应填"broke down"符合语境。故选D项。

When           another country, you should be aware of those differences and respect them.

visit

to visit

visiting

visited

考查非谓语动词。句意：当拜访另一个国家时，你应该知道这些不同之处并尊重它们。分析句子可知，空格处应填非谓语动词和when一起构成时间状语，逻辑主语you和visit之间是主动关系，应用现在分词。故选C项。

It is well-known that crack cocaine is a powerful             drug and users become           to it much more easily if they smoke it.

addicted; addict

addictive; addict

addicted; addictive

addictive; addicted

考查形容词辨析。众所周知可卡因是一种强大的令人上瘾的毒品，如果使用者吸了它更容易上瘾得多。addicted上瘾的，着迷的；addict"shi使沉迷；使上瘾”是动词；addictive “使成瘾的，令人沉迷的”。第一空表示“令人上瘾的”用addictive，故排除A，C项；become addicted to “对....上瘾”，第二空填addicted。故选D项。

---I'm sorry,but it's my seat.

---           I didn't know it's yours.

What if

I beg your pardon

That's all right

What for

考查交际用语。句意：---对不起，这是我的座位。---请原谅。我不知道这是你的。A. What if如果.....将会怎么样；B. I beg your pardon. 对不起，请原谅；C.That's all right没关系；D. What for为什么。根据"Idon't know it's yours."可知坐了别人的座位，请求别人原谅。故选B项。

There are 24 solar terms in a year. Grain Rain often starts in Apirl,the           month of the year.

Third

fourth

fifth

sixth

考查数词。句意：一年有24个节气。谷雨通常在一年中的四月开始。空格前有定冠词the,与可数名词单数month，要用序数词。根据

Grain Rain often starts in Apirl，可知四月份是一年之中的第四个月，要用序数词fourth。故选B项。