【题目】Oxygen helps the fish stay ________.

【题目】________ limited in the world.

【题目】Computers are useful. For example, they can ________ sending e-mail.

【题目】He’s fed the dog and the cat, _______?

【题目】When you're learning English, use it, ________ you'll lose it.

【题目】________ fog it is!

【题目】Come on! I have an interesting story ________ you.

【题目】Nowadays people can't live without electrical appliance such as ________ fans.

【题目】As a leader, he should have the ability of thinking about things ________ another way.

【题目】To build a road in the mountainous area is ________ real challenge.