杆件受到垂直于轴线方向的外力作用时所产生的变形，称为（）变形。A、弯曲B、压缩c、拉

小明想知道学校旗杆多高，他发现旗杆上的绳子垂到地面还多2m，当他把绳子的下端拉开10m后，发现下端刚好接触地面，则旗杆的高为（　　）

A．16m

B．20m

C．24m

D．28m

子类或对象具有延用父类的属性、事件和方法的能力，称为类的

A．继承性

B．抽象性

C．封装性

D．多态性

MY Chinese friend is going to the US and he is nervous about what to talk about. “Talk about the weather,” is my advice.

“How are you?” is often followed by comments about the weather. “Nice day today.” “Cold/hot enough for you?” “Will it ever stop raining?” “Some winter we’re having.” “Can’t remember a winter/summer so cold/hot.” “Whew, it’s hot out there.”

These introductory statements are often followed by a long conversation entirely about weather conditions. Past, present and – with global warming – speculation (推测) about the future.

Our fascination with weather might seem silly, but the real purpose behind those endless discussions is small talk. Weather’s a safe topic of conversation. As a group, we Americans seem to enjoy chatting with those around us. Whenever we stand in line at the grocery store, we tend to engage in this sort of conversation with other people standing in line with us. If I were seated next to another American on any form of public transport, I’d expect both of us to make some harmless comment about the weather as a way of acknowledging (承认) each other’s presence (存在). At parties, the weather is a common topic, especially with those you are meeting for the first time.

In contrast we are taught to avoid certain topics like religion and politics. Weather is neutral (中性的); you don’t have to have an opinion about it, just make a statement of a fact. What is truly interesting is the fact that we can go on and on about it.

My Chinese friend has a hard time understanding why we put so much effort into this topic – and why I warn him about bringing up much more “interesting” subjects like salaries or how much something costs.

Sometimes it is tricky (复杂的) to wend (行走) one’s way through winding cultural roads, especially those that are never taught in books.

小题1:What does the writer suggest her Chinese friend should talk about with people in the US? (No more than two words)

小题2:Why do Americans enjoy talking to people around them about the weather, in writer’s opinion? (No more than ten words)

小题3:List four topics that people should avoid talking about in the US. ( No more than 5 words)

对于鸡蛋中铁的叙述正确的是()。

A．含量较低

B．营养价值很低

C．主要存在于蛋清中

D．以上都不正确

循环气冷却器在开车时需要向（）中通入（）来给反应器升温。