Why __________ (do/does) lions have sharp teeth? - Because ________ (it/they) eat meat.
do, they
Why __________ (can/can't) a penguin fly? - Because it ________ (have/has) short wings. .
can't, has
Why __________ (do/does) zebras have stripes? - Because ________ (it/they) hide in the grass
do, they