强酸型阳树脂在使用中常常会受到（）等杂质的污染。
A、悬浮物
B、重金属
C、油
D、胶体硅
参考答案：A, B, C
The football team from our school _____ all the other and _____the award at
last.[ ]
A. beat; beat
B. won; won
C. beat; won
D. won; beat
20万U维生素D相当于多少质量()。
A．20mg
B．15rug
C．50mg
D．25mg
E．5mg
