Which of the following characteristics is not desirable for the materials used to make the helmets?
A.Great heat resistance
B.Great impact resistance
C.High density
D.Great strength
正确答案:High density
Which of the following characteristics is not desirable for the materials used to make the helmets?
A.Great heat resistance
B.Great impact resistance
C.High density
D.Great strength
正确答案:High density