Cargo booms must be weight tested to recertify the Safe Working Load (SWL) every _______.
A.year
B.two years
C.four years
D.five years
正确答案是D
Cargo booms must be weight tested to recertify the Safe Working Load (SWL) every _______.
A.year
B.two years
C.four years
D.five years
正确答案是D