—What does PM 2.5 mean?
—It's a professional ________ indicating the condition of air pollution.
| A．term | B．item | C．number | D．mark |
What an accident! If the driver_________ carefully, things would not be as they are.
| A．has driven | B．drove | C．had driven | D．was driving |
The price_________recently. I wonder whether it will remain so.
| A．was going up | B．went up | C．has gone up | D．has been going up |
What I said and did at your house last night_________just between you and me.
| A．is | B．are | C．have been | D．had been |
He waited with his companion_________the rescuers came, and then helped them carry her back down the mountain.
| A．when | B．until | C．unless | D．while |
It's_________for an employee of this company to work seventy" hours a week since the competition is fierce in the industry.
| A．ordinary | B．usual | C．average | D．regular |