spare no effort 和 spare no efforts的区别

都是”不遗余力“的意思,但是根据前面的主语的单复数来决定后面的”effort"的单复数
例如：
We should spare no efforts to further your interests 我们应该不遗余力的争取你的利益
I shall spare no effort to restore world trade by international economic readjustment,
but the emergency at home cannot wait on that accomplishment.
虽然我将不遗余力通过国际经济重新协调所来恢复国际贸易,但我认为国内的紧急情况无法等待这重新协调的完成.