Past.

(+)He prepares breakfast.

(-)He didn't prepares breakfast.
(?)Did He prepares breakfast? yes , he did.

(+) Denise eat lots of apples.
(-) Denise didn't eat lots of apples.
(?) Did Denise eat lots of apples? yes, He did.

(+)He loves to travel.

(-) He didn't loves to travel.
(?) Did he loves to travel? yes, she did.

(+)they will go for a walk
(-) they went for a walk
(?) Were they for a work? no they weren't.

(+) I was born in 1992.
(-) I wasn't born Wednesday.
(?) Was I born in 1992? yes I was.