18. Don't worry! He ____ no attempt to leave. He will stay here to help you.
| A．made | B．got | C．had | D．Tried |
Parents should pay attention to areas _______ their child is having difficulty and spend extra time to help him or her master those skills.
| A．as | B．where | C．why | D．when |
We apologize for any inconvenience you _______ have been caused by the delay of the flight.
| A．may | B．would | C．must | D．need |
The police say there is a $50,000 _______ for any information that helps them find the killer.
| A．income | B．fee | C．bill | D．reward |
Most whales must come up for air after several minutes, _______ a few can stay under water for an hour or more.
| A．while | B．or | C．for | D．so |
The numbers that researchers get from the experiments can be _______, just like number puzzles.
| A．disappointing | B．inspiring | C．worrying | D．confusing |