If it ________ , I’ll go to the zoo.

We must be strict ________ ourselves. —I think so.

Of the two sisters, Lucy is _____ one ,and she is also the one who loves to be quiet.

With his eyes ________ the work attentively, he didn’t know what was happening outside.

In today’s competitive economy, ________ everyone is trying to do more with less, you’ve got to figure out a way to profit from the very beginning.