Alec never carried a gun to my knowledge.

亚历克据我所知从不带枪。

To my knowledge, hehas never been late before.

据我所知他从未迟过到。

To my knowledge, she has never been late before.

据我所知，她从未迟到过。

To my knowledge , she has never been late before .

据我所知，她从未迟到过。

To my knowledge , there is no such idiom in english.

据我所知，英文里并没有这样的成语。