您正在看的高中三年级是:The USA。 t midnight they crossed the river and took possession of the village. 他们半夜渡江，占领了那个村庄。

　　The old couple took possession of the house about 30 years ago. 那对老年夫妻大约在30年前就买了那所房子。

　　The policeman came and took possession of the thief's bag. 警察来了，把小偷的包夺了过来。

　　11，It was also thought that by removing their main supply of food, the Native Americans would be forced to give in. 当时还有人认为，断掉了主要的食物来源，土著人就会被迫屈服。

　　1)remove vt.除去，排除，消除(get rid of)。例如：

　　Remove his name from the name list. 把他的名字从名单中勾掉。

　　We tried to remove his doubts and let him tell the truth. 我们设法消除他的疑虑，让他说出事情的真相。

　　If you can remove their fears, the villagers will not run away. 如果你能打消村民的恐怖情绪，他们就不会逃走。

　　2)give in 投降，让步，同意。例如：

　　They refused to give in and fought to the end. 他们拒绝投降，战斗到底。

　　Mother kept inviting Mrs Smith to stay for lunch, and finally she gave in. 母亲再三地邀请史密　斯太太留下来吃午饭，她终于同意了。

　　Mary usually has to give in to her big brother. 玛丽通常得听从她大哥的话。

　　12，Between 1850 and 1910 the bison population is thought to have fallen from 60 million to just a few hundred. 人们认为，在1850年到1910年之间，野牛的头数从6,000万头下降到只有几百头了。

　　本句是一个简单句，谓语动词用了被动语态。句子的意思相当于下列主动句：People think that between 1850 and 1910 the bison population fell from 60 million to just a few hundred.

　　to have fallen 是不定式的完成式，表示不定式的动作发生在谓语动词的动作之前，也就是说 to have fallen 　发生在is thought之前。后者是现在时，则前者是过去时。这可从上面的主动句中看出。又如：

　　I am glad to have met him. (=I met him and I feel glad.) 我遇见了他非常高兴。

　　He pretended to have read the book.(=He pretended that he had read the book.)他假装读过这本书。

　　She seems to have finished her work.(=It seems that she finished her work.)她好像已经完成了她的工作。

　　13，Thus one simple fact, a change in the number of bison, had an effect on the whole wildlife chain of the plains. 因此，一个简单的事实-野牛数目的变化对平原的整个野生生物链都产生了影响。

　　have an effect on 对……有影响，对……起作用。 effect后跟介词 on或 upon，effect 前也可以有形容词作定语。例如：

　　These agreements have an effect on both the buyer and the seller. 这些协议对买卖双方都起作用。

　　The arrival of the European settlers had a great effect on the life of Native Americans. 欧洲殖民者的到来对美洲土著人的生活有很大的影响。

　　The cold in spring usually has a bad effect on the growth of plants. 春寒通常对植物的生长不利。

　　The medicine had no side effects on your body. 这种药对你的身体没有副作用。

　　【语法-主语】

　　主语可以用名词、数词、动名词(或动名词短语)、不定式、词组、复合结构、从句等来充当。

　　1、名词作主语

　　Our Party and government pay great attention to the development of agriculture and industry .

　　2、数词作主语

　　Two-thirds of the students live at school .

　　3、动名词(或动名词短语)作主语

　　Running makes my heart beat faster .

　　4、不定式作主语

　　To talk with our friends is a pleasure .

　　For her to open the door was impossible .

　　注意：不定式作主语时谓语动词用单数，并且常用 it 充当形式主语。如：

　　It is important for us to master a foreign language .

　　5、用 it 作形式主语的句型有：

　　(1) It is + 形容词(possible , clear , true , necessary , likely , nice 等) + that

　　(2) It is + 名词 (a pity , no use , a fact , no wonder 等)+ that

　　(3) It + 不及物动词(follows , happens , turns out , goes without saying)+ that

　　(4) It is + 过去分词(thought , known , mentioned , said , eXPected , suggested ,

　　may be safely said , must be admitted , has been decided )+ that

　　6、词组或者复合结构作主语

　　Early to bed and early to rise makes a man healthy , happy and wise .

　　7、主语从句作主语

　　Is that you told me really true ?

　　What they are going to have at lunch hasn't been decided .

　　注意主语从句作主语时常被换用成 it 作形式主语，如：

　　It is a pity that he had made such a mistake .