I was on the phone when I smelt something ---- in the kitchenA buring B to be burnt 为什么不选B

I was on the phone when I smelt something ---- in the kitchenA buring B to be burnt 为什么不选B
I was on the phone when I smelt something ---- in the kitchen
A buring B to be burnt
为什么不选B

I was on the phone when I smelt something ---- in the kitchenA buring B to be burnt 为什么不选B
现在分词表示一种状态
或者这样理smell 是感官动词,感官动词一般+do表示知道全过程,+doing表示片断或正在进行

用现在时表示和on the phone 同时发生
强调我是在打电话的时候闻到的