▲pain 表示“努力”“辛苦”，总是用 pains 这样的复数形式。如：
He had written the book with great pains. 他呕心沥血写了这本书。
We must give him something for his pains. 我们必须给他点什么以便酬报他的辛劳。
▲另外，take (great) pains 其实是一个固定搭配，意思是“费心或努力（做某事）”。如：
She takes great pains with her work. 她工作兢兢业业。
Great pains have been taken to ensure the safety of passengers. 为确保乘客安全而不遗余力。
He has taken pains to study the problem. 他费尽了心血研究这个问题。
I took great pains to keep [in keeping] the house clean. 我费了不少心来保持房子整洁。
▲更多用法，请参考英语语法网的以下文章：

http://www.yygrammar.com/Article/201305/3303.html