necessity/nɪˈsesɪtɪ/
n.-ties1. 需要；必需； 必要Water is a necessity of life.水是生命必不可少的。
Out of necessity or out of interest, people go back to school for the common goal - to improve themselves.不管是出于需要，还是出于兴趣爱好，人们重返学校是为了一个共同的目标，就是提高自己。
2. 必需品Food and clothing are necessities of life.食物和衣服都是生活的必需品。
3. 贫穷，贫困She is now in necessity.她现在很穷。