What’s _____most useful invention in the 20th century? —_____ computer, I think.

Do you know the nearest way to the science museum?—Sorry, I’m a stranger. This is the first time I _________ here.

What __________ he do? — He __________ an actor.

Lily is coming by ________plane tomorrow. — Let’s go to ________ airport to meet her.

There are about more than five ___________ “left-behind” students (留守学生) in China.