为什么靠近导线的绝缘子劣化率高？
参考答案：
根据绝缘子串的电压分布规律（“Ｕ”型曲线）知道，靠近导线的绝缘子承受的分布电压高，所以运行中较易老化，劣化率高。
I asked her ______.
A．how long she had the bike
B．how long did she have the bike
C．how long she bought the bike
D．how long did she buy the bike
胃液中缺乏哪种成分可引起恶性贫血（）
A.内因子
B.红细胞
C.胃蛋白酶
D.白细胞
E.上皮细胞
