Ⅰ级（）

A.瘤细胞仅侵及表皮层内，即原位癌

B.瘤细胞已侵及真皮 * * 层

C.沿真皮 * * 层和网状层间扩展，但尚未侵及真皮网状层

D.侵及真皮网状层

E.已侵入皮下组织

The first communication satellite was used for the purpose of（）.

A.taking the place of the radio system

B.introducing a new life-saving system

C.saving the vessels in distress

D.improving the communication on land