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阅读以下说明，回答问题1-4。[说明] 设学校教学数据库的模式如下： S(SNUM，SNAME，AGE) SC(SNUM，CNUM，CREDIT，SCORE) C(CNUM，CNAME，TEACHER) T(TNUM，TEHCHER，POS，SAL) SNUM表示学生的学号，SNAME表示学生的姓名，AGE表示学生的年龄，CNUM表示选修课程的编号，CREDIT表示该课程的学分，SCORE表示课程的成绩，CNAME表示课程名，TEACHER表示任课的教师,TNUM表示老师的工作证号，POS表示教师的职称，SM，表示教师的收入。试定义下列完整性约束和规则： [问题2] 在关系SC中插入的元组时，其SNUM和CNUM的值必须分别在S和C中出现过。

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There is an old saying in English: "Laughter is the best medicine". Until recently, few people took the saying very seriously. Now, however, doctors have begun to investigate laughter and the effects it has on the human body. They have found evidence that laughter really can improve people’s health.Tests were carried out to study the effects of laughter on the body. People watched funny films, while doctors checked their heart rate, blood pressure, breathing and muscles. It was found that laughter has similar effects to physical exercise. It increases blood pressure, the heart rate and the rate of breathing; it also works several groups of muscles in the face, the stomach, and even the feet. If laughter exercises the body, it must be beneficial.Other tests have shown that laughter appears to be capable of reducing the effect of pain on the body.There is also some evidence to suggest that laughter helps the body’s immune system, that is, the system which fights infection.As a result of these discoveries, some doctors and psychiatrists (精神病学家)in the United States now hold laughter clinics, in which they try to improve their patients’ condition by encouraging them to laugh.1) Laughter really can (46) .2) In the first test, it was found that laughter has similar effects to (47) .3) Other tests have shown that laughter can reduce the effect of (48) on the body.4) There is evidence to show that laughter helps the body’s (49) .5) In the clinics, the psychiatrists try to improve their patients’ condition by encouraging them (50) . 50（）

Conversation 2[听力原文]9-10W: What’s going on hereM: You mean, what’s happening Well, constable, I’m trying to get out of the window and Freud here is helping me.W: Why are you climbing through the window and not leaving by the front doorM: Well. you see I can’t find the key and I’m in a hurry. Come on, Freud, we’re wasting time.W: Just a minute you two. I don’t think you’re telling me the truth. This isn’t your house, is itM: No. it’s my brother’s. I’m staying with him for a while.W: Is he at homeM: I’m afraid not. He’s just in jail for house-breaking at the moment what was the man doing（）

A. He’s trying to get out of the window.
B. He’s helping Freud.
C. He’s breaking into a house.
D. He’s leaving by the front door.

(四) [背景资料] 某工程位于某市中立交桥与体育场路口交叉处，总建筑面积4万多平方米，其中一号楼、二号楼和三号楼均为高层建筑。该屋面上有各种管道和屋顶花园设施等，针对该工程的使用功能和对防水、隔热要求高、难度大的特点，建设单位设计部门对防水保温隔热方案的设计和施工十分重视，经过实地考察并分析具体情况，通过精心施工，克服了各种困难，于1998年12月22日一起与其他项目验收为省优良工程，得到各方面的好评。请简述上一问中所提到的制度的主要任务。

设二叉树根结点的层次为O，对含有100个结点的二叉树，可能的最大树深度和最小树深度分别是______。