比较浅白的说法是：I am going to do it. 或I will do it. 再道地一点可以说：I gonna to do it.
比较文雅的说法是：I have made up my mind to do it. 或It is finalized to do so.
直接一点可以说：I decided to do so.如果想表达比较坚定的决心，可以说：
I determined to do so.
deside是决定的意思所以是:decide to do sth 答案补充 make a decision do sth
