从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
6. In the botanical garden we can find a(n) ______of plants that range from tall trees to small flowers. (05上海)
A. species B. group C. amount D. variety
7. Tomorrow he will take part in a job interview _________the interviewer is likely to ask some difficult questions.
A. that B. when C. whom D. where
