I didn't _____________ that! [ ]
A. know
B. knew
C. known
答案:A
容灾等级通用的国际标准SHARE78将容灾分成了六级。
若长期保存精液,其温度必须低于().
A.-196℃
B.-79℃
C.-130℃
D.-25℃
E.-50℃