Vitamin D helps our bodies make a special chemical, and this special chemical, ________, affects our brains, making us feel happy.
Weifang you see today is quitedifferent city from what it was 10 years ago.
— Have you taken the picture of me with the elephant? — Hang in there! I'll take ________ two of you.
We __________ booked. Look, this restaurant is almost empty.
________ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.
In no case _______ go _______ the law of nature or we’ll meet endless suffering.