Answer from cs61c-bx (Tuan Ha 16989532) for Question 1
WHILE statements and DO WHILE statements can be dropped. We only need IF and GOTO because with IF and GOTO (along with labels) we can create the same looping effects as those created by WHILE or DO WHILE. I think the designers of C include them all because each of them has their own advantages when dealing with specific tasks. For example, DO WHILE always performs the actions at least one time. By including them all, it is easier to understand and implement the codes.