题目内容：

以下每句均有错误，错误涉及一个单词的增加(∧)或一个单词的删除(\，其他错误为单词的修改。每处错误及其修改均仅限一词。

1.Tea was invented by an accident.

2.It said that they have known the secret.

3.A Chinese ruler calling, Shen Nong was the first to discover tea as a drink.

4.Some leaf fell into the water and remained there for some time.