In the heavy rain, people were made to take shelter in the nearest possible shop.

1. 主动式：made people take shelter；被动式：people were made to take shelter（人们被迫避雨）

2. in the nearest possible shop 是修饰 shelter 的定语。possible 经常与最高级连用，仍然是“（最）可能的”。由于前面有了最高级，possible 可以不必译出。