a. 不吝惜的, 慷慨的, 大方的, 严厉的, 不留情的, 不宽恕的
相关词组:
be unsparing in one's efforts
be unsparing of praise
在线英汉词典

unsparing的短语、例句：

unsparing adj ~ (in sth) 1giving freely and generously 慷慨的; 大方的
be unsparingin one´s efforts 不遗余力. 2 severe or merciless 严厉的; 不留情的
Nijinsky was unsparing in his demands for perfection. 尼任斯基对演技精益求精一丝不苟.