Polar bears live mostly on sea ice, which they use as platform for hunting seals

Polar bears live mostly on _____ sea ice, which they use as ___ platform for hunting seals.

   A. a; a       B. a; the     C. 不填；a    D. the; 不填

试题答案

C

解析:

sea ice 海冰, 是固定结构，不用冠词；platform平台，是可数名词。