Using completely with either word or totally is redundant. Uninterested means a lack of interest. If someone was drowned, that means someone held his or her head under water. Due to modifies nouns. His vigor was due to his diet of oysters.
Ecology is the study of the environment.
The teams lined up on either side of the field is incorrect. The teams lined up on both sides. FEEL Use this word for touching and feeling things, not emotions. Don't use it as a synonym for thinking or believing. Handbills and aviators are fliers.