The workers ____ (build) a new bridge near my house last year and I guess they will finish it next month.

点拨：____意为"当……时候"，后面通常接时间点，从句中谓语动词用短暂性动词。另外，while，意为"当……时候"， 后面只能接一段时间，不能接时间点，其引导的从句的动作或状态往往与主句的动作同时发生。

While we were walking home, it began to rain.＝ ____

—Because his classmates often make fun of him because of his stammer(口吃).