以下列举的事例中说法正确的是 [ ]
A.食用馒头可以补充糖类
B.用含亚硝酸钠的工业用盐腌制食品
C.服用大量含碳酸钙的药物来补钙
D.用甲醛水溶液泡制水产品并出售
答案:A
The teacher was surprised to see lots of people_____at the back of the room _____worried. [ ]
A.seating;looked
B.seated;looking
C.sitting;looked
D.sat;looked
滚动轴承的内圈和外圈均为基准件,并采用基孔制配合。