NBER Working Paper 和 NBER Working Paper5979 哪个是正确的（刊物名）,说下原因

where ( ) your father working?括号里面是is还是does啊 知道的说下 working working和work的用法 hard-working和working hard的各自意思 net working capital和working capital是不是一样的 Is Tom as hard-working as Sam?这句话正确吗?我想表达的是 汤姆和塞姆一样努力（勤奋）吗? he has been working on the paper. The dog is frightening.The man is working.哪个是现在分词?和动名词什么关系? hard working 和 word hard的区别 work hard和hard working的不同 hard-working的比较级和最高级 hard-working 和work hard的区别