吸气时出现脉搏显著减弱或消失的现象可见于A．主动脉瓣关闭不全  B．心包积液  C．

弹簧测力计下挂一金属块，在空气中时，弹簧测力计示数为10N，当把物体慢慢浸入水中时，弹簧测力计的示数将______，物体受到的浮力将______（变大/变小/不变）；当金属块的1/3浸在水中时，弹簧测力计的示数是8N，如果将它全部浸没在水中，弹簧测力计的示数又是______N．

与脑组织麻醉药浓度升高无关的是()

A．脑/血分配系数

B．血/气分配系数

C．吸入浓度

D．MAC

E．脑血流量

简述HE染色中二甲苯、酒精和水洗的作用?

You have probably seen ads (广告) in newspaper or on television for mail-order companies. Perhaps a catalogue (商品目录) has been sent to you. Why do people buy things they have not seen in person Some people believe that things can be bought more cheaply by mail. Another good thing about buying by mail is that it is easier and more enjoyable to sit at home and work through a catalogue than to shop around the stores. With a catalogue from a large company, you have your own shop window for almost everything you want to buy.
Buying from a catalogue is so easy. It saves the shopper’s time and trouble. Sometimes, it saves the shopper’s money, too. But people often buy more than they can really afford(付得起) or need, because many things look so good to them. They can probably pay a certain part of the full price—a down payment. Then they pay a certain amount of money every month until the goods is paid for in full. But by then they often find what they have bought are of no use at all.

Why do people buy things without seeing them in person
[A] To enjoy themselves.
[B] To save money and trouble.
[C] To get more than they need.

采用牺牲阳极法保护钢管免受腐蚀性土壤侵蚀，基本方法是( )。

A．每隔一定间距，连接一段非金属管道

B．连接消耗性阴性材料，使钢管成为阳极

C．连接消耗性阳性材料，使钢管成为阴极

D．钢管设涂层，使钢管成为中性