1. Let me explain this to you , because when you are talking to a person or a group of people . They would know who you are talking about right after you started a conversation.

For example, ( just imagine I am talking in Chinese)

A: Look at that girl , she(he<--if you say it in Chinese) is so pretty. <----You have mentioned that it's a girl ! why need use she or he?

B. We've got a new teacher , her name is Amy , she(he<----You know it's a girl by the name that person has  mentioned.) will be teaching us today.

C: I met a new friend last night, she( he ) is so cool. <----You don't know the gender, you will ask , oh or is he(she) a boy ? , then he would say that  oh it's a girl. And then you both continue the conversation.

Actually , Why People have been saying English is difficult to speak ? Because the Grammar always confusing people when you are trying to speak it with people , You always need to remember what kind of tenses you should use in your head before you speak with people. English is so confusing people , not the other way around.

For example, We went out to eat last last night . In Chinese , it has no tense needed to be changed, it would be like I go out to eat last night. Because you already tell the time before you start a conversation. You always give a name, a time, who when you start a conversation with other people .There should NOT be like was , is , were , ...so confusing people all the time. It makes English is so difficult to learn when it comes to speaking.

参考阅读：https://www.zhihu.com/question/19621773

所以说，你想要的正确答案可能是：

这是用来折磨汉语母语者的