While () along the shore, I found a lot of sea shells.

While () along the shore, I found a lot of sea shells.
A、walk
B、walking
C、to walk
D、walked
【正确答案】：B
【题目解析】：句意：当我在海边散步的时候，我发现了许多贝壳。当while引导的时间状语从句的主语与主句主语相同，且从句的谓语又是be动词时，那么从句中的主语和be可以省略因此，此处应用"While walking..."的形式替代"While I was walking",故选B。