北美12.18大作文是机经哪版的内容啊？

annybaobao

我记得做过一套题是什么，

  交朋友是不是一定需要共同的兴趣爱好？

  这次算是旧题吗？

annybaobao

补充一下小作文：

  There are 3 means to protect pine tree forest from pine beetle.

 1  low temperature in winter can kill larvae, freezing cold temperature can reduce the amount of beetle.

 2 pine tree automatically flush out sap to fill holes made by beetle, flush them out to protect itself

 3  wild fire can keep natural healthy balance of young and mature trees  of pine forest . Sufficient young trees is crucial to maintain forest. Because beetle like mature trees which diameter is more than 20 centimeters.

  NOW because of human activity, those three protection methods has been greatly weakened.

   1  green house effect , higher temperture in winter can't kill larvae.

   2  over exploration of underground water. Now pine trees can't flush out enough sap to protect itself.

   3  human management leads to less wild fire and lower proportion of young pine trees to mature trees