关于Just as与 so too搭配的用法？

metaviii

给位NN，在manhattan SC 8TH P183, 看到一个用法：

right：JUST AS the trains were lately yesterday, the buses are late today.
right: JUST AS the trains were late yesterday, SO TOO are they late today.

请教一下这个第二句，so 作为 FANBOYS的连词，与 JUST AS/AS，同时出现在一个句子中？ 这种情况，怎么理解。 我认为第二句的SO 不应该出现

长丝弓

第二句的so too用法是可行的
参见Macmillan词典，释义如下：
used for showing that there is a connection between two situations or actions
另有例句
Just as the body needs regular exercise, so too an engine needs to be run at regular intervals.
供参考