#学英语# Effective, Efficient, Effectual, and Efficacious

这四个单词是同义词，但是含义略有不同。 Efficacious 强调主语有能力来达到某个结果 （a detergent that is efficacious in removing grease).
Effective 强调主语有能力达到某个具体且特定的结果 （an effective rebuttal).
Effectual 强调达到想要的结果，特别是在某些具体情况下 (measures taken to reduce underage drinking have proved effectual).
Efficient 强调在避免太多（精力，时间，资源,等方面）损失情况下达到某个结果。
efficient 比较好区别，effectual重视实际结果，而efficacious 和effective 都强调能力，但也有细微差别。Effective略强调具体结果。
例子（转）
Say you're in IT, and there's an issue tracker nobody ever looks at. The accounting department complains that their software sporadically slows down. Your manager wants to ignore this, but doesn't want to appear to ignore this. So he says, 'put a ticket in the issue tracker.' This is an effective, ineffectual ass covering.
Something is ineffectual if it has no effect, it makes no difference. They do not even n