国家档案局对我国各类档案库温、湿度制定了标准，其遵循的原则是（）。

A.防止害虫对病案的危害

B.防止空气污染对病案的危害

C.有利于档案制成材料的耐久性

D.防止真菌的滋生

E.防止其他微生物的滋生

Sometimes we _____ be busy shopping in a supermarket, for it's more convenient to purchase online nowadays. [ ]

A. needn't

B. mustn't

C. shouldn't

D. can't