Today let's take a break from colors and look at a very common word. 是 - To be.
是 is pronounced shì in mandarin. It sounds very similar to the english word 'sure'
Since mandarin has no conjugation of verbs, you'll use this word directly whenever you want to say something is, was, will be.
我是快了 - (Wo shi kuaile) - I am happy.
那是我只狗 - (Na shi wo zhi gou) - That is my dog.