n[C] 引申意为“xx的来源”
Racial and cultural diversity has long been considered a source of strength for the US.
a source of income/delight/strength/happiness/progress
Liberty and autonomy are sources of human dignity.
翻译：Yao Ming and Liu Xiang are sources of pride for Shanghainese.
要真正掌握一个单词，很多时候查英汉字典还是不够的，有时甚至查英英字典也不够。我们需要在阅读时注意常见词汇的意思和常见搭配，在语境中掌握一个词的真正用法。
造句：Poverty is not the only source of unhappiness.
搭配：
1. adj+grounds
good grounds 正当的理由；reasonable grounds合理的依据；strong grounds 强有力的理由；sufficient grounds 充分的理由；legitimate grounds 合法的依据；valid grounds令人信服的根据
2. V+grounds
have grounds
The police had reasonable grounds for arresting her.
give grounds
His evasiveness gave grounds for suspicion. 他含糊其辞，让人有理由怀疑。
3. prep+grounds
on grounds 由于。。。的原因
Permission to open a mine was denied on environmental grounds.
on the grounds of 因为。。。的原因
He resigned on the grounds of ill health.
