The black and blue pen is very nice.为什么是is不是are

The black and blue pen is very nice.为什么是is不是are the blue pen is( ),( )is black. I like blue pen on the table.It is very nice 这句话改错 填空：The bags ______ blue and orange are very nice. the shoes are black and look very nice look为什么不加s blue,biong,girl,with,the,is,hair,eyes,very,and,nice如何连词造句 blue,blong,girl,with,the,is,hair,eyes,very,and,nice如何连词 black and blue means is? Tom is black and blue. The blue pen is his,and the green pen is hers.如果对,为什么要用hers? the chicken is very nice.how much are they?为什么是用复数 是My pen is black and white 还是用are?why?