If you continue to put on weight

If you continue to put on weight, you will have to ( ) a diet before long.
A、begin with
B、take
C、go on
D、start out
【正确答案】：C
【题目解析】：固定搭配 go on diet 节食。句子含义是如果你持续增重，不久之后你就要节食减肥了。