It's better to add 300 or 400 words with a little bit of prose,

It's better to add 300 or 400 words with a little bit of prose,

Nitrogen in air accounts for about () of the volume of air
The holes in the vertebrae are joined together to form a bone tube that holds ()
The blood circulation is to transport nutrition and () to all parts of the body

Nitrogen in the air accounts for about 78% of the volume of air
The holes in the spine join to form a bone tube that holds the spinal cord
Blood circulation is to transport nutrients and oxygen throughout the body

Questions about brackets
It's ( Dongdong’s) dictionary.
( )dictionary( ) it?

( Whose )dictionary( is) it?