While crossing the mountain area

While crossing the mountain area, all the men carried guns lest they（ ）by wild animals.

should be attacked

must be attacked

could be attacked

would be attacked

本题考查的是情态动词，lest后从句用虚拟语气谓语形式为should+动词原形，唯恐，以免；担心。在穿越山区的时候，所有的人都带着枪，以免被野兽袭击。