necessity
- 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"