It's good to know mistakes and correct them

知错───Know your mistake;改───change

If you don't know you're pregnant, you may mistake this bleeding for your period.───如果你不知道你已经怀孕，你可能会误以为你的经期来了。

If you find instruction you will know your mistake.───你要是看一下说明书就知道你错在哪儿了。