A study shows the students who are engaged in after-school  activities are happier than        who are not.

ones

those

these

them

考查代詞。句意：一項研究表明，參加課外活動的學(xué)生比不參加課外活動的學(xué)生更開心。空格處代詞與the students是對應(yīng)關(guān)系，可以用the ones 或者those替代。“them”指代前面提到的復(fù)數(shù)名詞，不能與the students形成對應(yīng)關(guān)系，“these”一般不用定語從句修飾。故選B項。

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語從句。句意：毫無疑問，中國是世界上有著悠久歷史，豐富文化的一個大國。分析句子可知，這個句型為 there is no doubt that 引導(dǎo)，表示“毫無疑問......”.本句為that that 引導(dǎo)的同位語從句，句意和句子結(jié)構(gòu)完整。故選C項。

How I wish every family         a large house with a beautiful garden!

has

will have

had

had had

考查虛擬語氣。句意：我多么希望每個家庭都有一個帶著美麗花園的大房子！此句是wish 引導(dǎo)的從句，從句要用虛擬語氣，根據(jù)wish 可知是與現(xiàn)在事實相反，從句一般用過去時。故選c項。

Though ____ the dangers of smoking to their health, smokers still find it hard to give up smoking.

aware of

are aware of

be aware of

考查狀語從句的省略：句意：雖然很多經(jīng)常吸煙的人已經(jīng)意識到抽煙對他們健康造成了很嚴(yán)重的后果，但是他們?nèi)匀话l(fā)現(xiàn)很難戒煙。Though引導(dǎo)的讓步狀語從句是省略句，完整的句子是：though smokers are aware of the dangers of smoking to their health。當(dāng)主從句的主語一致的時候，可以省略從句的主語和be動詞，選B

 Is _______ three hours _______ the poor boy to come to school on foot?

it; that it takes

there; that it takes

there; when

it; that

考查強調(diào)句。強調(diào)句的結(jié)構(gòu)為It’s + 強調(diào)部分 + that從句。本題強調(diào)時間狀語three hours。句意：可憐的男孩步行到學(xué)?；?個小時嗎？故A正確。