电缆敷设前应检查（）A、合理选择敷设线路 B、检查敷设路线上支架是否完好，有无妨碍运输

患者男。心悸，乏力，诊断为二尖瓣关闭不全，其杂音与相对性关闭不全的杂音相鉴别。支持后者的是（）。

A.粗糙

B.全收缩期杂音

C.可遮盖第一心音

D.不向远处传导

E.吸气时减弱

节点没有虚实之分，但是有紧前和紧后之分。

语法填空。

    One day a father and his rich family 1______ (take) his son on a trip to the country with the firm purpose

to show him 2______ poor people can be. They spent a day and a night on the farm of a very poor family.

When they got back 3______ their trip, the father asked his son, "How was the trip?" "Very good Dad!" "Did

you see how poor people can be?" the father asked. "Yeah!" "And 4______ did you learn?" 

    The son answered, "I saw that we have a dog at home, and they have four. We have a pool 5______

reaches to the middle of the garden; they have a creek (小溪) that has no end. We have imported lamps in the

garden; they have the stars. Our patio reaches to the front yard; 6______ have a whole horizon. " When the

little boy was finished, his father was 7______ (speech). His son added, "Thanks, Dad, for showing me how

'poor' we are!"

    Isn't it true that it all depends on the way you look at things? 8______ you have love, friends, family, health,

good humor and a positive attitude towards life-you've got everything! You can't buy 9______ of these things.

You may have all the material possessions you can imagine, provisions for the future, etc.; 10______ if you

are poor of spirit, you have nothing!

用原子吸收光谱法分析试样中的Tl，使用丙烷－氧气火焰，其温度为2800K，吸收线为377.6nm，它是由6p1－7s1跃迁产生的，试问火焰中Tl原子的激发态和基态数之比为多少？（已知：k=1.38×10-23J·K-1，h=6.63×10－34J·s）

一段时间以来由人民内部矛盾引发的群体性事件已经成为影响社会稳定的（）

A.主要问题

B.突出问题

C.重要问题

D.关键问题