血痕预实验最常用方法之一是（）。
A、联苯胺试验
B、酸性磷酸酶试验
C、苦味酸结晶试验
D、碘、碘化钾结晶试验
参考答案：A
我国《国民经济行业分类》是统一按照法人单位来划分的。（）
用所给词的正确形式填空。
1. They work out the difficult maths problem all by _____ (oneself) today.
2. What would you do if you _____ (win) a scholarship?
3. If it _____ (be) nice today, we _____ (go) for a picnic. But we were unlucky today.
4. If I _____ (have) time, I could play with you.
5. If you had got up earlier, you would _____ (catch) the train.
