下列药物抑制呼吸的强度依次为（） A.恩氟烷>氟烷>异氟烷 B.异_爱下问搜题

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问题单项选择题

下列药物抑制呼吸的强度依次为（）

A.恩氟烷>氟烷>异氟烷

B.异氟烷>恩氟烷>氟烷

C.恩氟烷>异氟烷>氟烷

D.氟烷>恩氟烷>异氟烷

E.氟烷=恩氟烷=异氟烷

答案

参考答案：C

解析：最低肺泡有效浓度（MAC）是指某种吸入麻醉药在一个大气压下与纯氧同时吸入时，能使50%患者在切皮时不发生摇头、四肢运动等反应时的最低肺泡浓度。因为MAC是不同麻醉药的等效价浓度，所以能反映该麻醉药的效能，MAC越小麻醉效能越强。恩氟烷MAC1.7%，异氟烷MAC1.15%，氟烷MAC0.75%。而抑制呼吸的强度与麻醉效能呈反比，故MAC与抑制呼吸的强度呈正比，MAC越大，抑制呼吸的强度越强。故答案应选C。

填空题

径向塔的特点是：气体呈（）流动，流速远较轴向流动为低，其压力降低较小，催化剂的生产强度较大，结构简单。

完形填空

阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上涂黑。
The Keeper of the River
An old man had been working for many years for a town．His job was to clear away natural waste from the pool water in the hills, which made up the lovely river flowing through the town nearby．Quietly and   , the old man guarded the hills,    the leaves and branches, and cleaned up the dirt that would have      and polluted the fresh flow of water．The town soon became a popular attraction for tourists．Elegant swans （天鹅） floated along the clear river and the view was so beautiful   words．
Years passed．One evening the town   met．As they reviewed the budget, one man's     caught sight of the salary     being paid to the seldom seen keeper of the river．He asked, "Who is the old man? Why do we   to employ him? No one in town ever     him． For all we know, the strange keeper of the hills isn't doing his job．His position isn't     any longer．" Then they voted to     the man．
For several weeks, nothing changed ．．．
By early autumn, the trees began to     their leaves．Small branches broke off and fell into the pools of the hills,    the flow of the shining water．One afternoon, someone noticed a slight yellowish-brown    in the river．A few days later, the water was much    . Within another week, an oily something covered some sections of the water along the banks, and a terrible      was soon sensed．Swans left, and so did the      . The only thing that was now visiting the village was disease and sickness．
Quickly , the    town committee called a special meeting．Realising their huge mistake in    , they rehired the old keeper of the river again, and within a few weeks, the river began to clear up．Swans and tourists came back again and new life returned to the small town in the Alps．
Never ignore the seeming smallness of a task, job, or life．They may all make a    .

C．masterpiece

A．embarrassed