mettle
/ˈmetl; `mɛtl/ n[U]
1 quality of endurance or courage, esp in people or horses 忍耐力, 勇气（尤指人或马的）
a man of mettle 有勇气的人
test sb's mettle 考验某人的耐力
She showed her mettle by winning in spite of her handicap. 那匹雌马尽管增加了负重而仍能获胜, 可见很有耐力.
2 (idm 习语) be on one's `mettle; put sb on his `mettle be encouraged or forced to do one's best; encourage or force sb to do his best 奋发; 激励某人尽最大努力
You'll be on your mettle during the training period. 你要在训练期间尽最大努力.
The next race will put him on his mettle. 下次赛跑他就要全力以赴了.