You _____ smoke when you see the sign. [ ]
A. must
B. should
C. mustn’t
D. needn’t
答案:C
下列内容不属于个人史的是()
A.受教育程度
B.习惯、嗜好
C.工业毒物接触情况
D.经济情况
E.配偶健康情况
Fire extinguishers used on ship’s are numbered by size I through V,with I being().
A.used for electrical fires only
B.the smallest
C.the most accessible
D.the most effective