正常人体内及体表多处有葡萄球菌存在而不引起人的疾病，其中最主要的带菌部位是（）

A.皮肤

B.咽喉

C.鼻腔

D.肠道

E.泌 * *

-It's 10 o'clock.  I must go now.

-It's raining outside. Don't leave __________ it stops.[ ]

A. when

B. since

C. while

D. until