—What does PM2.5 mean?
—It's a professional ________ indicating the condition of air pollution.
| A．term | B．item |
| C．number | D．mark |
—Why does she always ask you for help?
—There is no one else _______, is there?
| A．who to turn to | B．she can turn to | C．for whom to turn | D．for her to turn |
Please go _________the ship quickly. There is only fifteen minutes left.
| A．on the board | B．to aboard | C．on aboard | D．Aboard |
----- Did you visit her while you _____ in New York?
----- I _____ to, but I was extremely busy.
| A．stayed; was intending | B．was staying; intended |
| C．was staying; have intended | D．stayed; had intended |
John, look at the time. __________you play the piano at such a late hour?
| A．Must | B．Can | C．May | D．Need |
The new laws___________reducing the heavy traffic have come into___________.
| A．aiming at ; use | B．are aimed at; effect |
| C．aimed at; affect | D．that are aimed at; effect |