—I paid 200 dollars for the necklace. I think it's much too expensive.—Expensive? I don't agree with you. You so before you _______ it.
The Yangtze River, China’s longest, has been affected by a severe drought, ________ the lowest level of rainfall this year since 1961.
Professor Smith, along with his assistants, _________on the project day and night to meet the deadline.
There was so serious a matter that I had no choice but _________ the police.
The new research team was led by the ________engineer.
—Will you come? —________you promise not to invite Mary.