12.Ourservicepersonnelworkforclientsonawidevarietyofsites,manyof_______aretoughindustrialenvironmentsthatareunsuitableforlaptopsorPDAs.
A.whom正确答案C
B.them
C.which
D.that
12.Ourservicepersonnelworkforclientsonawidevarietyofsites,manyof_______aretoughindustrialenvironmentsthatareunsuitableforlaptopsorPDAs.
A.whom正确答案C
B.them
C.which
D.that