Polar bears liveon sea ice which they use as a platform for hunting seals.A. mostB. almos

问题补充：

Polar bears liveon sea ice, which they use as a platform for hunting seals.

A. most

B. almost

C. nearly

D. mostly

答案：

A. most

B. almost

C. nearly

(答案→)D. mostly

解析：句意：北极熊主要是生活在海冰上，他们用来作为猎捕海豹的一种平台。mostly

主要地，故选D。