It was eventing_________ we reached the small town.

这里不是强调句型
一before.
1.It was/will be+时间段+before...过了…才…
eg:It was three years before he finished the work.他花了三年才完成这项工作.
It will be three years before he finishes the work.他得花三年才能完成这项工作.
明白了吗?要看清真整个句子之后再做结论,如果要用that 的话就要改成It on was eventing_________ we reached the small town.要加个介词了.

不是所有的it is ……that……都是强调句型的，要根据句意进行判断的。