Someone was heard ___ the stairs.

问题描述:

Someone was heard ___ the stairs.
a.come up b.to come up c.went up d.goes up

come up 有走上来的意思.
被动后面接不带to的不定式短语.要把to补充出来.如 hear sb do sth=sb be heard to do sth
所以选B
翻译是 有人被听到走上了楼梯