'Know' in the Bible

Now we know that the law is good if any one uses it lawfully,

(but if one does not know how to conduct his own house, how shall he take care of the assembly of God?)

but if I delay, in order that thou mayest know how one ought to conduct oneself in God's house, which is the assembly of the living God, the pillar and base of the truth.

forbidding to marry, bidding to abstain from meats, which God has created for receiving with thanksgiving for them who are faithful and know the truth.