乳剂由于分散相和连续相的比重不同,造成上浮或下沉的现象为
A.表象
B.破裂
C.酸败
D.乳析
E.层析
参考答案:D
When the boss came in, these workers pretended to________ carefully.
A.working
B.be working
C.work
D.have been working
硫化氢气体有臭鸡蛋味。