The teacher wants his students _________ hard. [ ]
A. work
B. works
C. working
D. to work
答案:D
由于装配原因导致的危及人身、财产安全的产品缺陷属于()
A.检验缺陷
B.制造缺陷
C.告知缺陷
D.指示缺陷