Our teacher is always busy preparing lessons
until 11 o’clock at night, ______we students have gone to sleep.
| A．that time | B．by which time |
| C．by that time | D．which time |
Pine trees, of which there are almost one hundred _____, are found throughout the North Temperate Zone.
| A．species | B．samples | C．specimens | D．Standards |
The salmon dish was _______, wasn’t it?
| A．success | B．the success | C．a success | D．successes |
The conference had been held to discuss the effects of tourism ___ the wildlife in the rainforest.
| A．in | B．on | C． at |
D．with |
Specialists may be useful to _____ a situation and suggest solutions.
| A．analytical | B．analyze | C．analysis | D．analyst |
Problems _____ because they were lack of communication.
| A．raised | B．rose | C．arose | D．aroused |