It was in the factory _________ his friend worked _______ he picked up a lot of experience.

Birds’singing is sometimes a warning to otherbirds________away.

Stephen Hawking believes that the earth is unlikely to be the only planet _______ life has developed gradually.

. —-Do you often use Baidu—-Yes, it’s one of ___________Internet search engines.

He spends as much time as he can _______English.