What is double yarn single yarn?

do you mean dk or double knit yarn ? if so this is basically equal to USA sport yarn. It is non American version and knits at between 5-6 stitches to the inch using a number 5 - 6 needle ........ OR...

you just grab 2 sticks and go

we yarn because there is no enough oxygen in body

Double knitting refers to the "weight" of the yarn--how 'thick' is the yarn. DK or double knit is a a light worsted weight yarn. DK typically makes 5-6 stockinette stitches per inch when knitting....

A "yarn" is a story or tall tale -- swapping yarns is when one of you tells a story and then the other one "swaps" by telling another one. Another type of yarn swapping is a party for knitting...