so have questions…这个句子如何剖析

As smartphones have multiplied, so have questions about their impact on how we live and how we work.

参考答案翻译：伴随智能手机的激增，关于智能手机对大家生活和工作的影响的问题也层出不穷。

后面的分句是so have questions…这个句子这么剖析？主语是哪个？这是倒装吗？questions为何用第三人称单数？

so have questions about their impact on how we live and how we work.

这是倒装句。等于：

questions about their impact on how we live and how we work have multiplied too.

因为要和前面的as从句呼应，as..., so...。所以构成了so开头的倒装句。