necessary/compulsory.导航词义：必要的

1. necessary:adj. 必需的，必要的.普通用词，多指由客观因素决定的，是必不可少的。

Water is necessary for life.

水是生命不可或缺的。

It is necessary to perform an operation on him.

必须对他实施手术。

It is not necessary to wear a business suit.

不一定要穿商务套装。

If necessary, we can always change the date of our trip.

必要的话，我们随时可以改变旅行的日期。

2. compulsory:adj. 必须做的，规定的，义务的.指由法律、上级命令等规定或强制的。

compulsory circulation/education/insuranc

强制流通/义务教育/强制保险

Questions 1-6 are compulsory.

1至6题为必答题。

Is military service compulsory in your country?

你们国家实行义务兵役制吗？

Swimming is compulsory at their school.

在他们学校，游泳是必修课。

Many young men in that country tried to get away from compulsory military conscription.

那个国家的很多年轻人试图逃避强制征兵的政策。

全部

1·There is a compulsory course in statistics.

有一门统计学的必修课。《牛津词典》

2·Certain courses are compulsory, others are optional.

某些课程是必修的，其他是选修的。《牛津词典》

3·It is compulsory for all motorcyclists to wear helmets.

所有骑摩托车的人都必须戴头盔，这是强制性的。《牛津词典》

4·Workers won their fight to stop compulsory redundancies.

工人赢得了阻止强制裁员的斗争。《牛津词典》

5·English, Maths, ICT and Science are compulsory subjects.

英语、数学、信息技术和自然科学是必修课。《柯林斯英汉双解大词典》

6·They have campaigned strongly for compulsory registration of dogs.

他们大力开展了狗的强制性登记活动。《柯林斯英汉双解大词典》

7·He believes that the study of history should be compulsory in school.

他认为在学校里学习历史应该是强制性的。《柯林斯英汉双解大词典》

8·They said that compulsory identity cards would infringe civil liberties.

他们说强制办理身份证会侵犯公民的自由。《牛津词典》

9·Compulsory sterilization represented social engineering of the worst sort.

强制性绝育象征着社会工程的最低手段。《柯林斯英汉双解大词典》

10·It was settled by compulsory arbitration.

此事已通过强制性仲裁得到解决。《新英汉大辞典》

义务的

1·It is compulsory that students should attend all the classes.

学生有义务上参加所有的课程。

2·In China, it is our responsibility and obligation to take compulsory education.

在中国，接受义务教育是我们的责任和义务。

3·With compulsory education from the age of five or six, her role as chief educator of her children soon ceases.

随着义务教育从五岁或六岁开始，她作为教育她孩子的角色很快停止了。

4·While serving a compulsory stint in the military, Nurmi entered a 20-k march carrying a rifle, a cartridge belt, and a knapsack.

在军中服义务役的时候，努尔米带着一支步枪、一条子弹带和一个背包参加了20公里行军。

5·Everyone has their own copy of the textbook supplied by the central education authority, Monbusho, as part of the concept of free compulsory education up to the age of 15.

作为免费义务教育理念的一部分，在15岁之前，每个人都有中央教育机构 Monbusho 提供的教科书。

强制性

1·It is compulsory for all motorcyclists to wear helmets.

所有骑摩托车的人都必须戴头盔，这是强制性的。《牛津词典》

2·They have campaigned strongly for compulsory registration of dogs.

他们大力开展了狗的强制性登记活动。《柯林斯英汉双解大词典》

3·He believes that the study of history should be compulsory in school.

他认为在学校里学习历史应该是强制性的。《柯林斯英汉双解大词典》

4·It was settled by compulsory arbitration.

此事已通过强制性仲裁得到解决。《新英汉大辞典》

5·There are no compulsory standardized tests in Finland, apart from one exam at the end of students' senior year in high school.

除了在学生高中最后一年的那一次考试，芬兰没有其它强制性的标准化考试。

必修的

1·Certain courses are compulsory, others are optional.

某些课程是必修的，其他是选修的。《牛津词典》

2·Education is valued greatly in Japanese culture; maths is recognized as an important compulsory subject throughout schooling; and the emphasis is on hard work coupled with a focus on accuracy.

在日本文化中，教育极受重视；数学被视作整个学校教育过程中一门重要的必修科目；刻苦努力和精益求精的精神也颇受重视。

3·English is a compulsory subject at this level.

英语在这一级别是必修科目。《牛津词典》

4·The danger of prescribing a course of compulsory studies is that it implies that a man who has gone through the prescribed course ipso facto knows all there is to know for an educated man.

必修课程的规定，其危险在于它义涵一个人只要读完这个课程，便已在事实上知晓了一个学者所应知晓的事情。

5·In June, the Ministry of education announced that institutes of higher education would be required to establish compulsory courses on college students' mental health.

今年6月，教育部下达通知称，各大高校将按要求设立有关大学生心理健康的必修课程。

(1)compulsory education义务教育

(1)compulsory course必修课

(1)compulsory insurance强制保险

(1)compulsory license强制许可

(1)nine-year compulsory education九年制义务教育

(1)compulsory subject必修课