问题描述：
which of the following are true statements?
i.All symmetric histogram have single peaks.
ii.All symmetric bell-shaped curves are normal.
iii.All normal curves are bell-shaped and symmetric.
btw：bell-shaped curve不是本来就symmetric吗,为啥题目还要指出啊,另外可以给一下normal curve的定义吗!
i.All symmetric histogram have single peaks.
ii.All symmetric bell-shaped curves are normal.
iii.All normal curves are bell-shaped and symmetric.
btw：bell-shaped curve不是本来就symmetric吗,为啥题目还要指出啊,另外可以给一下normal curve的定义吗!
问题解答：
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