n a condition requiring relief
n anything that is necessary but lacking
n the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior
n a state of extreme poverty or destitution
v require as useful, just, or proper
v have need of
v have or feel a need for
r in such a manner as could not be otherwise
adv. (只与must连用)必须地