正确答案: A

甲的行为当然发生效力

题目：春节时，14岁的甲用自己的压岁钱在某商场购买了价值2000多元的电动玩具，则 （　　）

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学习资料的答案和解析：

[单选题]Which of the following is the best title of the article?

根据以下内容，回答下面的题目。Researchers have found that REM (rapid eye movement) sleep is important to human beings．This type of sleep generally occurs four or five times during one night of sleep lasting five minutes to forty minutes for each occurrence．The deeper a person’s sleep becomes, the longer the periods of rapid eye movement．There are physical charges in the body to show that a person has changed from NREM (non-rapid eye movement) to REM sleep．Breathing becomes faster, the heart rate increases, and, as the name implies, the eyes begin to move quickly．Accompanying these physical changes in the body is a very important characteristic of REM sleep．It is during REM sleep that a person dreams．According to the passage, how often does REM sleep occur in one night?

REM Sleep

[单选题]阶级社会形成以来的婚姻家庭制度是 （　　）

一夫一妻制

[单选题]骨骼肌的兴奋一收缩耦联不包括 （　　）

肌浆网中的Ca+释放入胞浆