to a certain extent 在某种程度上；to the best of one’s ability 竭尽..的所能；We have exerted ourselves to the utmost. 我们已使出全部力量。
9.Then in June, as if by magic, a never-setting summer sun gives birth to hundreds of species of arctic plants to cover the ground. 然而到了六月份, 如同奇迹般地, 终日不落的太阳使得北极成百上千种动植物恢复了生机, 长得覆盖了地面。
1 )magic n. 魔力(法)；by magic 魔术般地, 不可思议地as if by magic 好像使用魔术般地；
All trees budded, as if by ma gic, over one night.
所有的树像魔术般地一夜之间发出了嫩芽。
A group of buildings spread out as if by magic like mushrooms.
一群建筑像蘑菇一样不可思议地耸立着。
2 )never-setting 是现在分词结构作定语修饰sun, 意为“ 不落下的”；working people 劳动人民；a crying baby 哭泣的婴儿；barking dogs 正在吠的狗；operating machine 正运转的机器。
以上这类构成现在分词的动词常为不及物动词, 现在分词表示的行为, 动作有正在进行之义, 且同它修饰的名词有主动关系, 即其名词是行为的执行者或动作的发出者。
3 )give birth (to)生；产生She ga ve birth to a girl last night. 她昨晚生了一个女孩。
Social contradictions ga ve bir th to the French Revolution.
社会矛盾导致了法国大革命。
10. The animal life on the tundra is usually rich for an environment that seems so harsh. 在如此严酷的环境中, 冻土带的动物通常繁多。
1 )rich adj. 丰富的, 多的a rich harvest 丰收；rich oil 沃土；rich practical experiences 丰富的实践经验；a rich country 富饶的国家
2 )for prep. 至于, 就..而言(有拿出来对照之意)The day is warm for April. 在四月份, 这样的天气算是暖和的了。
He is tall for his age. 就他的年龄而言, 他算是个子高的了。
The landscape is too beautiful for words. 景色美得无法言传。
That is good enough for me. 对我来说, 那是十分好了。
3 )that seems so harsh 作定语从句修饰environment。
11. Herds of arctic deer move from place to place in search of food. 一群群北极鹿游来游去寻找食物。
1 )herds of.一群群(常指温驯动物)herds of dear 一群群鹿；herds of cattle 一群群牛；a herd of sheep 一群羊；a herd of cattle 一群牛；汉语中“ 一群”这个单位词, 英语要用不同的单位词去搭配。比如文中紧接的下一句中的bands of 译为汉语也是一群群, 但常同凶猛的动物搭配。a band of wolves 一群狼；a band of dogs 一群狗；a school of fish 一群鱼；a flock of chickens 一群鸡；a group of people 一群人；a swarm of
ants 一群蚂蚁。
2 )search n. 搜寻(查), 当用作不及物动词时, 同for 介词连用。in search of 寻找, 寻求。
Some dogs are barking and running in sea rch of a rabbit.
有些狗正在吠和奔跑, 寻找一只野兔。
search for 寻找, 搜寻The professor is sea rching for his subject books.
那位教授正在找他的专业书籍。
12. However a variety of birds migrate to nest and feed during the summer. 但有很多种鸟夏季迁徙到这里筑巢、觅食。
1 )variety n. 种类；a variety of 种种, 多样, 各种。
Iron has a va riety of uses. 铁有种种用处。
for a va riety of reasons 由于种种原因；
by a va riety of means 用各种手段；
in a va riety of ways 用种种方法。
2 )to nest and feed 是不定式, 在句中作目的状语。nest v. 筑巢, 巢居；feed v. 觅食, 如: a feeding cattle 正吃食的牛。
13. The wet, marshy land produces a large number of insects that provide food for the smaller birds that, in turn, provide food for the arctic fox and the wolf. 潮湿的沼泽一样的土地繁殖了大量的昆虫, 这些昆虫便成为体型较小的鸟类的食物来源, 而这些小鸟又为极地狐和狼所捕食。
1 )a number of 大量的；number 前面可以用定语修饰它a large number of 许多的.., 大量的..。
2 )that provide.and the wolf 作定语从句修饰insects。
3 )provide.for.为..提供..
The father provides food and clothes for our family.
父亲供给家里人衣食, 养家活口。
Many hands provide great strength for the construction.
修建这个建筑物时, 人多力量大。
The guide provided guidance for the tourists.
向导为游客们提供指导。
4 )that, in turn, .and the wolf 是定语从句中套的定语从句, 修饰birds。
14. Their presence and the presence of the pipeline they built represented a major change in the environment. 他们的到来及他们起的输油管道给环境带来了很大的变化。
1 )presence n. 到场；存在, 其形容词形式是present 意为“ 到场的”。
Your presence is requested. 请你出席。
We shall be glad to have your presence.
你如能出席, 我们将感到很高兴。
He was present at the meeting. 他出席了会议。