Mary and Den...at school. (X)
Mary and Den weren't at school.
Cars are faster/slower than bikes.
faster
The children...at home yesterday. (V)
The children were at home yesterday.
He...in China. (X)
He wasn't in China.
Hippos are fatter/thinner than wolves.
fatter
They...in England. (V)
They were in England.
Girls are older/younger than women.
younger
Summer is colder/hotter than winter.
hotter
Giraffes are taller/shorter than rhinos.
taller
A month is longer/shorter than a year.
shorter