以下关于相对不应期的表述，正确的是（）
A.心肌细胞对阈刺激不发生任何兴奋反应的时期，称为相对不应期
B.应用比阈刺激值低的刺激能引起兴奋反应的时期，称为相对不应期
C.应用比阈刺激值高出2～4倍强度的刺激，可以引起扩布性激动反应的时期，称为相对不应期
D.应用比阈刺激值高出2～4倍强度的刺激，不能引起兴奋反应的时期，称为相对不应期
E.应用大于阈刺激值100倍强度的刺激也不引起兴奋反应的时期，称为相对不应期
参考答案：C
解析：应用大于阈刺激值100倍强度的刺激也不引起兴奋的间期，称为绝对不应期。应用比阚刺激值高出2～4倍强度的刺激，不能引起兴奋反应的时期，称为有效不应期。应用比阈刺激值高出2～4倍强度的刺激，可以引起扩布性激动反应的时期，称为相对不应期。
Long ago，in a small village of Wakefield lived two farmers，Harry and Peter．Harry was very hard．working while Peter was 36 ．Every day Harry got up early and came home late，but Peter walked around for fun． One summer there was no 37 and the crops(庄稼)were dying．Harry thought，“I must do something to save these crops，or they shall die．”With this 38 in mind，he went out to find a river so that he could dig a canal(沟渠)to his field．He walked on and on, feeling tired and thirsty．After a 39 search，he found a river full of blue water．He was very happy．He started digging a canal to his field. 40 it was noon his wife sent their daughter to bring Harry home 41 lunch．But Harry did not go．He did not want to leave his work unfinished．He completed his work 42 at night．He Was very satisfied． He went home。had a good meal and 43 into a sound sleep． Peter did the same．But he was not at all determined(有决心的)．He also 44 digging a canal to his field but he didn’t have his work completed．His field did not get 45 water and all his crops died． Harry’s field would be watered when needed．He had a good harvest because of his hard work．
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