'Doubtless' in the Bible

If I be not an apostle unto others, yet doubtless I am to you: for the seal of mine apostleship are ye in the Lord.

Or doubtless does he speak {for our sake}? For it is written {for our sake}, because the one who plows ought to plow in hope and the one who threshes [ought to do so] in hope of a share.

for [doubtless] there have to be factions among you, so that those who are of approved character may be clearly recognized among you.

There are doubtless many different kinds of languages in the world, and all have meaning.