阑尾位置常有变异是由于（）.
A.阑尾系膜过长
B.盲肠不固定
C.中肠旋转异常
D.局部慢性炎症影响
E.胚胎发育过程中退化不全
参考答案：B
读问题,再回答。
1. Do you like winter?
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2. What's your favourite season?
3. What do you do on the weekend?
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4. What's the weather like today?
5. What's your mother's favourite season?
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安全生产管理的目的是（）.
