Finding information on the Internet is easy. The ______ is how you can tell whether the information is useful or not.
| A．ability | B．competition |
| C．challenge | D．knowledge |
19. Russia is a country which extends across _____ .
| A．Asia | B．Europe | C．Asia and Europe | D．Africa |
20. "What can I do for you?" or "May I help you?" is a pet phrase used by _____ .
| A．an assistant engineer | B．an assistant manager |
| C．a helper | D．a shop assistant |
21. Move a few steps, and the oil-paintings look better ______.
| A．in the distance | B．at once | C．in the open air | D．at a distance |
22. In fact, the untruthful words made ____ on me. You must answer for that.
| A．a surprise attack | B．much damage | C．a personal attack | D．a great harm |
23. Every Monday morning, all the teachers and students in our school stand at ____ as our national flag is raised.
| A．attention | B．attentions | C．at ease | D．Attentively |