Keep away from the dog , _______it will bite you.
| A．and | B．so |
| C．or | D．but |
--- How did you pay the workers? --- As a rule, they were paid ______.
| A．by hour | B．by the hour | C．by hours | D．by an hour |
. Several years later he ___ writer.
| A．become | B．turned | C．become a | D．turned a |
__ U.S.A. lies on the other side of ___.
A. The; PacificB. /; PacificC. The; the Pacific D. /; the Pacific
Beyond ___ stars, the astronauts could see nothing but _____space.
| A．the; / | B．/; the | C．the; the | D．/ ; / |
He is ___new comer to ___ chemistry but he has made a few important discoveries.
| A．/, / | B．a, / | C．a, the | D．the, the |