我这句英文写的对不对There are enormous amounts of trees which have been cutted down every year so that it cause a great degradation on our ability of preventing the sandstrom.

我认为degradation用在此处不合时宜。可以用weaken或difficult等。
比如：there are enormous of trees which have been cutted down every year so that it makes a great difficulty to prevent the sandstorm.
there are enormous of trees which have been cutted down every year so that it weakens our ability of preventing the sandstorm.

cut 这个英文词不管怎样就只可以是cut ，没有说cutted ，cutting之类的

这个句子问题多多啊.你这句的意思是：很多树每年都被砍掉,目的是导致我们减少防止沙尘暴的能力.so that表目的,不宜用在此句.cutted应该改成cut.不是这些树每年都被砍,而应该是每年都有很多树被砍.应该改成类似这样的句子：Each year lots of trees have been cut down.As a result(Consequently),our ability to prevent sandstorm has been weakened.

There are enormous amount of trees have been cut down every year and it has caused a great degration on our ability to prevent the sandstorm.