Please tell me the differences. What are the differents between "He is in black"and"He is in the black" "Mr.Smith took a chair"and "Mr.Smith took the chair" Thanks.

First notebook entry: Introducing myself I'm Bridget,a freshman in college.I enjoy learning English so I choose English as my major in college.I do well in all the exam but I know it can't prove anything.There are still a lot for me to learn or I will be left behind. Everyone's learning English on campus,so I need to be better.Maybe I will study abroad after graduating ,I'm not sure yet.Anyway,I'm going to forget about the pass and move forward.