Water and air are _______ to human beings.We can not live without them.A.harbourB.functionC.definiteD.essential

问题描述:

Water and air are _______ to human beings.We can not live without them.
A.harbour
B.function
C.definite
D.essential

选择D,意思是水和空气对人类来说都是必不可少的,我们离开他们无法生存.
essential就是必不可少的意思