子系统的相互依存关系类型大约有______。 A．汇合型 B．程序型 C．往复型 D

从下面方框中选择适当的词填入短文中，使短文通顺正确（注意有些词要用适当的形式）。方框中有两个多余的词。

walk   they   take   make   light   candle   bad

Our environment is getting小题1:）_____________ than before. Now more and more people realize that we should do something to help the Earth. Here are the things we can do to help the Earth: We can recycle glass, metal and paper. We shouldn’t throw小题2:_____________ in the garbage can（垃圾箱）! We can小题3:_____________ instead of driving cars! We should try to小题4:_________ short showers and turn off all the小题5:_____________ and the TV when we leave the room. All of these things will help the Earth.