knuckleball

['nʌklbɔ:l]

n. [棒](投手投出的)不旋转球

例句与用法：

If you want to pass that exam, you'll have to knuckle down (to some hard work).

你要想考试及格，就得开始下功夫(苦干)了。

词形变化：

异体字: knuckleball | 名词: knuckleballer |