It was this factory that my father used to work.这个句子是强调句吗?但是this factory 放回原来的句子后也不完整阿?

It was this factory that my father used to work.
这个句子是强调句吗?但是this factory 放回原来的句子后也不完整阿?

这个句子是强调句.应该是It was this factory that my father used to work in.

英文有误，应该是It was this factory where my father used to work.