荧光抗体活性鉴定常采用琼脂双扩散法，效价一般应大于1:16。()
参考答案：对
— What a clean and bright classroom, isn't it?
— Yes, it's always clean and bright because it _____every day.
A. cleans
B. cleaned
C. is cleaned
D. was cleaned
为解决某一特定问题而设计的指令序列称为( )。
A．语言
B．程序
C．软件
D．系统
