女性，30岁。停经2年余，疑诊催乳素瘤而进行血清催乳素检查，其值为多少可确诊（）

A.<200μg/L

B.>200μg/L

C.>300μg/L

D.<300μg/L

E.<100μg/L

_____ of the surface (表面) of the earth is covered with water.[ ]

A. First third

B. Two thirds

C. One three