休克的根本病因是（）
A.血压下降
B.中心静脉压下降
C.心排出量下降
D.有效循环血量下降
E.微循环障碍
参考答案：D
解析：休克的特点是有效循环血量锐减，有效循环血量依赖于血容量、心搏出量及周围血管张力三个因素。有效循环血容量是单位时间内通过心血管系统进行循环的血容量，并不包括贮存于肝、脾和淋巴血窦中，或停滞于毛细血管中的血容量。
Have you ever offered a helping hand to those who are in trouble? One day, two ______ were walking along the road to school when they saw an old woman carrying a large basket of pears. They thought the woman looked very ______. They went up to her and said, “Are you going to town? If you are, we will help carry your basket.” “Thank you,” ______ the woman, “you are very kind. You see I’m weak and ill.” Then she told them that she was now going to market to ______ the pears which grew on the only tree in her little garden. “We are all going to the ______.” said the boys. “Let us have the basket.” And they took hold of it, one each side. They walked ______ with the heavy basket, but happily. The other day, I saw a little girl stop and ______a piece of orange peel (皮), which she threw into the dustbin (垃圾桶), “I wish ______ would throw that on the sidewalk,” said she. “Someone may step on it and fall.” Perhaps some may say that these are not ______ things. That is right. But such a little thing shows that you have a thoughtful mind and a feeling heart. We must not wait for the ______ to do great things. We must begin with little things of love.
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