硫代乙酰胺试液用于
A．氯化物检查B．硫酸盐检查C．葡萄糖中的重金属俭查D．磺胺嘧啶中的重金属检查E．铁盐检查
参考答案：C
25. Her grandmother has taught in this school _______ she became a school teacher.
A．before
B．since
C．until
D．After
就色光来讲，三原色指的是（）。
