徒劳无功: prove futile; beat the air; be a wasted effort; burn daylight; carry coals to new castle; catch shadows; catch the wind in a net; come to naught; draw water in [with] a sieve; end in smoke
鞭策: (驱使; 督促) spur on; urge on; give an impetus to; encourage 短语和例子以先烈的革命精神鞭策自己 spur oneself on by thinking of the revolutionary spirit of the martyrs; 我们要经常鞭策自己努力学习。 we should constantly urge
致一位徒劳无功的朋友: to a friend whose work has come to nothing
