多选题
Because howler monkeys rarely come out of the trees in their arboreal habitat, the continued well-being of the rain forest is ______ to their survival.
【正确答案】
C、D
【答案解析】[解析] ●逗号说明前后同义重复。
●空格与rarely come out of the trees in their arboreal habitat(很少踏出它们栖息的树林)同义重复。
●marginal不重要的，tangential不重要的，indispensable重要的，imperative重要的，expeditious迅速的，baneful有毒的。答案选CD。
●注：这里marginal和tangential是干扰项，同表示“不重要的”。