“坚韧的”用英语怎么说？

运动员在比赛中表现出坚韧的斗志.The athletes displayed great tenacity throughout the contest.用于提取这种油的树脂取自于一种矮小坚韧的树。The resin from which the oil is extracted comes from a small, tough tree.棍子落下去,他觉得好像打在坚韧的橡胶上.He felt the rubbery solidity...