The purpose of learning Mandarin Chinese is to out it into the actual use. However, the language you learn at school may not always useful when it comes to the real conversations. Therefore, you should learn in the life by talking with the native people. 该A就A，该B就B is one sentence pattern learners often hear which is used to indicate that it should go on as the common law goes and should not be influenced by a certain event. For instance, 学生也不能一天到晚埋在书堆里，该学就学，该玩儿就玩儿. Sometimes, 就can be omitted to make it该吃吃，该睡睡.

If you meet something unhappy or makes you angry, you may want to express your feeling with some impolite words. But it is still a good way to learn Chinese language. For instance, 该死 is always said to indicate to be angry at or show disgust to somebody’s speech or act or phenomenon, or to self-reproach one’s own fault. You can say真该死！你怎么又把我的车撞坏了！

One thing you should pay attention to is that sometimes it can be 该死的, but it is used not for self-reproach. What’s more, it carries the tone of complaint or curse. Of course, female also uses it sometimes. But when the female uses it to curse the intimate partners, she pretends to be coquettishly angry. You can say该死的，这破电脑又死机了.

During the process when you study at Chinese school in China, you may joke with your friends to warn them. Then, the expression告诉你（们）is a good choice. It is often used as parenthesis for the purpose of reminding or warning the other party to pay attention to what is going to be said later. Let’s say one dialogue as follow.甲：你还会弹钢琴？乙：没想到吧？告诉你，我从三岁起就开始学了.

It is usually used to remind the others of some unusual aspects of a person or something, carrying the tone of showing off. Besides, it can be used to threaten the other party, carrying the tone of warning like我告诉你，你要是再这样下去，迟早要进监狱.