下列属于生态系统的是（  ）

①拿别人的缺点、缺陷、姓名开玩笑　
②经常帮助同学，特别是身体有残疾的同学　
③喜欢散播小道消息，专门讲同学的糗事　
④上课时给同学们讲故事听，让同学们发笑

（1）Swallows fly back to the ____ part of the country in winter every year.(南方)
（2）The space sleeping bag is fixed to the walls to prevent ____ .（飘浮）
（3）I am not sure whether the watches are those ____ .(绅士）
（4）You will get much____ if you give up eating fast food.(苗条)
（5）It is said that this kind of the car is____ designed for her.(特别的)
（6）In winter you’d better keep____  warm enough to stay healthy.(you)
（7）We____  could not believe our ears when we heard the surprising news.(simple)
（8）The water in the river is ____ . You can drink it without cooking.(harm)
（9）Works of MoYan is very popular among Chinese____  .(read)
（10）My daughter hopes to go abroad for ____ (far) study next year.