___________there are many different types of food, some animals spend their lives eating only one type.
| A．Since | B．Unless | C．Once | D．While |
Just as our teacher often ________ it, success is ninety percent attitude.
| A．gets | B．makes | C．puts | D．means |
Many studies already link the first meal of the day to better classroom .
| A．performance | B．function | C．behavior | D．display |
During the students’ first teacher training year, they often visited schools for the _____ of lessons.
| A．examination | B．investigation | C．inspection | D．observation |
Not knowing what version of iPad to choose, _____．
| A．some advice was given to Barbara | B．Barbara had to consult her IT teacher |
| C．so Barbara had to consult her IT teacher | D．Barbara's IT teacher gave her some advice |
．It was commanded that the coal mine survivors ____ to the nearest hospital for treatment．
| A．must send | B．be sent | C．would be sent | D．should send |