There are over 58,000 rocky objects in ______ space, about 900 of which could fall down onto ______ earth.
| A．the; the | B．/; the | C．the; a | D．a; / |
．________ relation between China and Russia has developed steadily since Vladimir Putin was reelected ________ president last May.
| A．The; the | B．A; the |
| C．The; / | D．A; / |
I have learned that it's taking ________ long time to become ________ person I want to be.
| A．the; a | B．a; the |
| C．the; the | D．/; a |
Because of H7N9 bird flu, all the chicken markets in Shanghai have been closed and won't open until further ________.
| A．sign | B．symbol |
| C．contact | D．notice |
One reason for her ________ for city life is that she can have easy access to places like shops and restaurants.
| A．reference | B．preference |
| C．performance | D．consequence |
—What does PM 2.5 mean?
—It's a professional ________ indicating the condition of air pollution.
| A．term | B．item |
| C．number | D．mark |