我听到身后有脚步声，迅速转过身。

I heard ___footsteps behind me and quickly turned round.

街上挤满了人，你甚至能听到他们的脚步声！

The streets were thick with people, and you could even hear their ___footsteps!

在寂静的图书馆里，唯一的声音是图书管理员轻柔的脚步声。

In the silent library, the only sound was the soft ___footsteps of the librarian.