酶
参考答案:酶是活细胞产生的具有催化作用的有机物。
I can ____ swim ____ skate. I'm going to have some training next year. [ ]
A. either; or
B. neither; nor
C. both; and
D. not only; but also
为了使计时器控件Timer1每隔0.5秒触发一次Timer事件,应将Timer1控件的__________属性设置为__________ 。