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__

　　答案及解析:

　　1.had-have

　　这里没有语境表明这个动作或者状态发生在过去某个时间点以前，所以用过去完成体不合适。

　　2.from-in

　　manifest something in something 意思是“在……方面表现出来”。例如：

　　His frustration manifested itself in his silence and inactiveness。

　　3.^altered-and

　　这里要看出并列的几个名次词组是 extend and thickness…、permafrost thawing、coastal erosion、changes in ice sheets and ice shelves、altered distribution and abundance of species，三个斜体的and并不是连接这几个并列项的，所以必须在最后一项altered distribution and abundance of species前加上并列连词and。

　　4.more-/

　　later本身已经是比较级，不用再加more。

　　5.so-as/since

　　这里要理清主从句的因果关系，从上下文看，应该说“冰层变薄”是因，“放牧驯鹿变得困难”是果，所以应该把so 改成as或since。

　　6.colder-warmer

　　文章谈的是气候变暖问题。“冬季变冷”显然是与整个文章的逻辑不符。

　　7.very-/

　　very不修饰形容词或者副词的比较级。(觉得这里把very 改为much 也没问题)

　　8.projections^-that

　　projections后面的从句是同位语从句，同位语从句的引导词that不可以省略。

　　9.^Arctic-the

　　“北极”Arctic前要加定冠词。

　　10.cause-causing

　　as well as相当于介词，其后不直接跟动词，应该是名次或动词-ing分词。