necessities
The necessity of something is the fact that it must happen or exist.
There is agreement on the necessity of reforms.
关于改革的必要性已达成了共识。
As soon as the necessity for action is over the troops must be withdrawn.
一旦军事行动的必要性不复存在,部队必须撤离。
A necessity is something that you must have in order to live properly or do something.
Water is a basic necessity of life.
生命离不开水。
A situation or action that is a necessity is necessary and cannot be avoided.
The president pleaded that strong rule from the centre was a necessity.
总统争辩说,实行高度的中央集权是一种必然。
of necessity
If you say that something is of necessity the case, you mean that it is the case because nothing else is possible or practical under the circumstances.
large families where children, of necessity, shared a bed.
孩子们势必会共睡一床的大家庭。