Tom ought not to( )me your secret,but he mean no harm .A,have told B,tellC,be tellingD,having told.

A
ought to 相当于should，后面加动词原形
所以D错误
这里要表达的意思是，本来不该告诉你，却告诉你了
用ought not to have done
所以，只有A正确

ought to 情态动词,后面加动词原形.
Tom ought not to(B )me your secret,but he mean no harm .A,have told B,tellC,be tellingD,having told.
汤姆本不应该告诉我你的秘密,但是他没有想伤害你.