【題目】Oxygen helps the fish stay ________.

【題目】________ limited in the world.

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

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

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

【題目】________ fog it is!

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

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

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

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