举例说说加法交换律、加法结合律、乘法交换律、乘法结合律、乘法分配律．

When you live with other people at school, it’s important to keep a good relationship with your roommates. Here is some advice.

★ Set rules together.  Rules are important. It’s necessary to set up rules with your room-mates together. You can talk about things you like and dislike. 小题1:              

This can make all of you comfortable to live in the same room.

★ Clean up the room. 小题2:             If you just throw your dirty clothes away or don’t take out the trash, no one in your room can be happy.  Although it’s hard to clean up your room every day, you need to clean it up at least twice a week.

★ Respect others’ privacy (尊重…隐私). Don’t take or use anything from your roommates without asking! If your roommates know that, he or she must be unhappy. 小题3:                

★小题4:             If you want to keep a good relationship with your roommates, you should spend some time together. In this way, you can know more about each other and find out what you have in common.

小题5: Which of the following is TRUE?

A．You can use anything from your roommates.

B．There is no need to set rules with your roommates.

C．You can spend some time with your roommates.

D．There is no need to clean up your room.

2011年春节前后，内地游客在港澳两地纷纷抢购进口奶粉，以至于当地出现了“奶粉荒”。这表明，消费者的不信任已经达到不仅对国产奶粉质量安全不信任，对在大陆销售的进口奶粉也持怀疑态度的程度。这启示我国企业在经营过程中要

①诚信经营，树立良好的信誉和企业形象　②遵守经济法规和市场道德，承担社会责任

③完善市场规则，规范市场秩序　       ④扩大生产规模，保障市场供应

A．①②

B．②③

C．③④

D．①④

液压传动系统中节流阀通过改变（　　）来控制流量的大小。

A．工作开口的大小

B．流通方向

C．流通速度

D．弹簧力的大小

《律师法》中所称的律师是指依法取得律师______证书，为社会提供法律服务的执业人员。
填入横线部分最恰当的一项是( )。

A．职业
B．执业
C．专业
D．从业

针叶树、常绿阔叶树种、落叶阔叶树种中抗性最强的是（）