tougher

adj.更困难的

形容词tough的比较级.

Humans have the tougher time ascending in harmlessness as compared with dolphins and whales. 相比海豚和鲸鱼，人类在提升入无害中有着更困难的时期。

But as climate change causes plants to peak earlier, caribou newborns that eat the plants face tougher odds for survival. 但是当气候变化的原因植物高峰前，北美驯鹿新生儿吃植物面对更困难的机率为了生存。