Chemical pollution will bring about a threat to agriculture and food chain, and ________ to human health.
The question of _______ English will continue changing in the future is easy _______.
She looked around, but the tall man was nowhere______.
The sun was shining brightly, ________ everything there ______ more beautiful.
—Now that you like the cell phone so much, why not carry it back? —Well, you know, I’m a student, and I can’t afford ________ mobile phone.
Loulan, once a small, wealthy commercial city, is believed by many people___________over gradually by sandstorms from AD 200 to AD 500.