英语词汇“necessary”的释义、区别辨析及用法例句-英语同义词词典

necessarynecessary /ˈnesəˌseri/ adjective 1 necessary and important► necessary

if something is necessary, you need to have it or do it:

My doctor thinks it is necessary for me to have an operation.

Some fat is necessary in your diet to provide heat and energy.

Make sure you have all the necessary documents for your trip, like your passport and ticket.

► essential

if something is essential, you need it in order to do something or for something to happen:

Oxygen is essential for plants and animals to live.

► vital

if something is vital, it is extremely important and you will have serious problems if you do not have it or do it:

It is vital that you turn off the electricity before touching the wires.

► crucial AWL

important and necessary, because other things depend on it:

Learning through play is crucial for the development of young children.

► critical

critical means the same as crucial:

Having a positive attitude is critical to achieving your goals.

► imperative (formal)

very important and needing to be done or dealt with immediately:

It is imperative that the report is ready by tomorrow.

ANTONYMS ➔ see unnecessary ➔ see importantADVERBS: necessaryYou can make the adjectives necessary, vital, crucial, critical, and imperative into adverbs by using an -ly ending: The company's future will necessarily depend on whether it can satisfy its customers. | Are these weapons vitally needed for national defense? | The attention a baby gets from its parent is crucially important to its development.The adjective essential can be made into an adverb, but it has a different meaning.2 necessary because a rule or law says you must► required

something that is required is necessary in order to do or achieve something, and someone in authority says you must do it:

The book is required reading for the class.

To be elected, a candidate must receive the required number of votes.

► compulsory

something that is compulsory must be done because a rule or law says that you must:

English classes are compulsory for all students.

► mandatory

something that is mandatory must be done because of a law:

Wearing a helmet when riding a motorcycle is mandatory.

► obligatory (formal)

something that is obligatory must be done because of a rule or law:

In Israel, military service is obligatory for boys and girls.

ANTONYMS ➔ see optional

单词	necessary
例句	necessarynecessary /ˈnesəˌseri/ adjective 1 necessary and important► necessary if something is necessary, you need to have it or do it: My doctor thinks it is necessary for me to have an operation. Some fat is necessary in your diet to provide heat and energy. Make sure you have all the necessary documents for your trip, like your passport and ticket. ► essential if something is essential, you need it in order to do something or for something to happen: Oxygen is essential for plants and animals to live. ► vital if something is vital, it is extremely important and you will have serious problems if you do not have it or do it: It is vital that you turn off the electricity before touching the wires. ► crucial AWL important and necessary, because other things depend on it: Learning through play is crucial for the development of young children. ► critical critical means the same as crucial: Having a positive attitude is critical to achieving your goals. ► imperative (formal) very important and needing to be done or dealt with immediately: It is imperative that the report is ready by tomorrow. ANTONYMS ➔ see unnecessary ➔ see importantADVERBS: necessaryYou can make the adjectives necessary, vital, crucial, critical, and imperative into adverbs by using an -ly ending: The company's future will necessarily depend on whether it can satisfy its customers. \| Are these weapons vitally needed for national defense? \| The attention a baby gets from its parent is crucially important to its development.The adjective essential can be made into an adverb, but it has a different meaning.2 necessary because a rule or law says you must► required something that is required is necessary in order to do or achieve something, and someone in authority says you must do it: The book is required reading for the class. To be elected, a candidate must receive the required number of votes. ► compulsory something that is compulsory must be done because a rule or law says that you must: English classes are compulsory for all students. ► mandatory something that is mandatory must be done because of a law: Wearing a helmet when riding a motorcycle is mandatory. ► obligatory (formal) something that is obligatory must be done because of a rule or law: In Israel, military service is obligatory for boys and girls. ANTONYMS ➔ see optional
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