这是一个钢笔,它是蓝色,所以这是个蓝色的钢笔怎么用英语说?

this is a pen ,it's blue ,so it's a blue pen

yellow黄色

white白色

green绿色

orange橙色

purple紫色

red红色

black黑色

this is a pen, it is blue ,so this is blue pen.

how mang kinds of color do you like?

This is a pen, it is blue, so this is a blue pen