One of the most important questions they had to consider was _____ of public health. 
| A．what | B．this |
C．that | D．which |
It is obvious to the studentsthey should get well prepared for their future.
| A． | as | B． | which | C． | whether | D． | that |
Could I speak tois in charge of International Sales please?
| A． | who | B． | what |
| C． | whoever | D． | whatever |
－Is there any possibilityyou could pick me up at the airport?
－No problem.
| A． | When | B． | that | C． | whether | D． | what |
The last time we had great fun was _____ we were visiting the Water Park.
| A．where | B．how | C．when | D．why |