—It's hot. Would you like some icecream?—I'd like some, but I'm .A. in a dietB. on a dietC

—It's hot. Would you like some icecream?
—I'd like some, but I'm .
A. in a diet
B. on a diet
C. on diet
D. in diet

A. in a diet(答案→)B. on a dietC. on dietD. in diet解析：句意：上文，真热啊。你想吃些冰激凌吗？下文，我想吃一些，但是我正在节食。Be on a diet是固定用法，意思是节食，选B。

这个解释是对的