单项选择题 Rite of Passage is a good novel by any standards; （） , it should rank high on any list of science fiction.

单项选择题The chances of a repetition of those unfortunate events are （） in deed.

A．distant
B．slim
C．unlikely
D．narrow

单项选择题The diversity of tropical plants in the region represents a seemingly （） source of raw materials, of which only a few have been utilized.

A．exploited
B．controversial
C．inexhaustible
D．remarkable