下列各句中，没有语病的一句是（ ）

To live on Mars, you need to wear boots which ________ to prevent you from floating off into space.

vels sell best and have made him famous, butbefore that no one could have imagined how great a role he ______ in theliterary world

Jenny keeps two pets. One is a dog, ______ is a rabbit.

Didn’t you find the film exciting—_____, I nearly fell asleep half way through it!