Changes in climate that had already taken place are manifested __1__ from the decrease in extent and thickness of Arctic sea ice, perma- __2__ frost thawing, coastal erosion, changes in ice sheets and ice shelves, altered distribution and abundance of species. __3__ Nowadays snows melt earlier in the springtime. Lakes, rivers and bogs freeze much more later in the autumn. Reindeer herding __4__ becomes more difficult so the ice is weak and may give way. __5__ Nowadays winters are much colder than they used to be. __6__ Occasionally during winter time it rains. We never expected this;we could not be ready for this. It is very strange. The cycle of the yearly calendar has been disturbed greatly. Warming over northern land areas has been very greater than elsewhere in the world. The __7__ changes are due to human modification of the concentration of greenhouse gases during the 20th century, leading quite directly to the projections the Artic will warm by several times as much during the __8__ 21st century as it did during the 20th century. The amplified warming in Arctic, in turn, directly contributes to overall global warming, as __9__ well as cause changes that create impacts over the rest of the globe. __10__

答案：

1.had-have。這里沒有語境表明這個動作或者狀態(tài)發(fā)生在過去某個時間點(diǎn)以前，所以用過去完成體不合適。

2.from-in。manifest something in something 意思是“在……方面表現(xiàn)出來”。例如：His frustration manifested itself in his silence and inactiveness。

3.^altered-and。這里要看出并列的幾個名次詞組是 extend and thickness…、permafrost thawing、coastal erosion、changes in ice sheets and ice shelves、altered distribution and abundance of species，三個斜體的and并不是連接這幾個并列項的，所以必須在最后一項altered distribution and abundance of species前加上并列連詞and。

4.more-/。later本身已經(jīng)是比較級，不用再加more。

5.so-as/since。這里要理清主從句的因果關(guān)系，從上下文看，應(yīng)該說“冰層變薄”是因，“放牧馴鹿變得困難”是果，所以應(yīng)該把so 改成as或since。

6.colder-warmer。文章談的是氣候變暖問題�！岸�季變冷”顯然是與整個文章的邏輯不符。

7.very-/。very不修飾形容詞或者副詞的比較級。(覺得這里把very 改為much 也沒問題)

8.projections^-that。projections后面的從句是同位語從句，同位語從句的引導(dǎo)詞that不可以省略。

9.Arctic-the�！氨睒O”Arctic前要加定冠詞。

10.cause-causing。as well as相當(dāng)于介詞，其后不直接跟動詞，應(yīng)該是名次或動詞-ing分詞