really, June, there's quite a lot more the the bible than juts reading it. After all, you read it in English whilst it was written in Hebrew, Aramaic and Greek. Trying to arrive at a text to translate isn't that much easier.
For the Old Testament, we have a couple of near complete Hebrew manuscripts to compare with the Hebrew texts preserved by the Jewish community to this day. The Hebrew ext has been well preserved and we can be fairly sure of the Hebrew text. However, not all the words are that well know with some appearing very infrequently in the text so we can still be stuck to translate them. That's how the KJV came up with 'unicorn' whereas other translations use some like 'wild ox' The complications come when you realise that there is another copy of the OT in existence from 200BCE. It is called the Septuagint (LXX) and is a translation into Greek of the Hebrew texts yet it has complications because it is quite a bit longer that Hebrew texts you are familiar with. The difference is, roughly, that which Protestant Bibles call the Apocrypha. (The Dead Sea Scrolls have copies in Hebrew of both versions.)
For the New Testament there are lots and lots of fairly complete not so complete and fairly incomplete manuscripts as well as fragments.The text of putting together the text as we think it was when it was written is a monumental one. There was a Greek text that was 'edited' by [wiki]Erasmus[/wiki] which was the basis of the KJV - I say edited because Erasmus, under pressure from the printers did little with the latter parts of the text. Since then we have been refining the text and as new discoveries turn up, trying to get the text into better form, The United Bible Society publishes what is, for translators, a fairly definitive text. However even that has lots of footnotes as to which word, when manuscripts differ was used and the other possibilities.
I hope you can see, June that even getting to what we hope is near to the original text is quite a job that it is no means certain is right but is the best we have so far managed. Editors working with the text, however, notice things about the text that causes them to comment. For example, the last few verses of Mark's gospel are rather different from the Greek of the main part of the gospel. There's no definite proof, but it is widely thought that change in the Greek comes about because someone added the verse well after the gospel was written. The same applies to some of Paul's letters which are considered non-genuine Paul as well as various other bits in the text. It is a little sad that the reader in English cannot see the differences though any good modern translation will have a footnote about significant passages indicating that they make no be original.
So you see, June, the whole question of the text of the bible, and hence which verses are quoted and said to be non-original, is quite a topic and not the simple thing it looks on the surface. So, next time you open the bible to look up something, take a look at the footnotes and see what the editor though about the passage you were reading.