Why does oxygen move from the alveoli into the pulmonary capillary blood?

Partial pressure of oxygen inside the alveolus is higher than in pulmonary capillary vessels, that allows oxygen molecules to diffuse into the blood.  

This is what i found on google“ the monomers combine with each other via covalent bonds to form larger molecules known as polymers. in doing so, monomers release water molecules as byproducts. this type of reaction is known as dehydration synthesis, which means “to put together while losing water. in the process, a water molecule is formed.” i hope this you