labor in vain

• 徒劳

labor in vain的用法和样例：

例句

1. It is vain to attempt to root out heresy by force.
   试图用暴力消除异端邪说是徒劳的。
2. Faith is not built on vain disquisitions.
   信仰并不奠立于那种徒劳的穷根究底。