why is this still in the book of.?

It would be nice if you spoke english.

D&C was basically the early doctrine and history of the restored church.

Most of it is still the same but mormons also believe in continual revelation. Certain doctrines were in place to help establish the restored church. When they were no longer necc they were changed. Polygamy is one of those. Very few early church members actually practiced polygamy and it was a calling, not just something anyone could decide to do. The eternal concept of plural marriage still exists in the church doctrine, but it is not ness or needed on earth today.

We believe the prophets of our particular time speak for God on behalf of the church as they did in the past. Although we can gain knowledge and truth from past doctrine, prophets today know the people of today the best. They know the church's and the peoples needs and concerns now.

In the same book is the revelation by the prophet that announces the termination of the practice of polygamy.

Mormons are not ashamed of that part of their past, as long as it is portrayed accurately.

if you keep reading you will see in the D and C 49:16

16 Wherefore, it is lawful that he should have one wife, and they twain shall be bone flesh, and all this that the earth might answer the end of its creation;

"doctorants. and covants"? You continue to amaze me, silver_foxx, that you could be so ignorant and still function in daily modern life. But then, getting that welfare check every month, you don't really need to function, do you?