it is kind of strange, that you ask in chinese, but this is baidu, so we all understand it in one way or the other.
i can only give answer to first question:
anything between 5000 and 400000 words.
small encyclopedia had 45000 words. My large Webster encyclopedia has quarter million words?and Collins concise dictionary has 324 thousand words.
both are from the USA, but contain also real english, not only American english.
这是一种奇怪的，你问中国人，但是这是百度，所以大家都明白它以某种方式或其他。
我只能给回答第一个问题：
5000和40万字之间的任何东西。
小百科有45000字。我的大百科全书韦伯斯特有四分之一万字
柯林斯简明词典有324000字。
无论是来自美国，但也含有地道英语，不仅美国英语。
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