necessity
英 [nɪ'sesɪtɪ]
美[nə'sɛsəti]
	    - n. 需要;必然性;必需品
 
英英释意
- 1. the condition of being essential or indispensable
 
- 2. anything indispensable;
 - "food and shelter are necessities of life"
 - "the essentials of the good life"
 - "allow farmers to buy their requirements under favorable conditions"
 - "a place where the requisites of water fuel and fodder can be obtained"