what are you driving at是甚么意思﹖

mcchan

drive at即try to say，指「想要说」，或「意思是」，例如﹕
I listened attentively to his long rambling speech, but could not make out
what he was driving at.
我注意倾听他杂乱无章的冗长发言，但不明白他指的是甚么(An English-Chinese
Dictionary of Idioms)

因此，what are you driving at即what are you trying to say，指「你究竟是指
甚么」，例如﹕
What are you driving at﹖You must explain yourself more clearly!
你这话究竟是甚么意思呢﹖你必须好好解释清楚﹗