Tom’s mother always told him not to smoke again, but _____ didn’t help.
A. he B. it
C. which D. as
Tom’s mother always told him not to smoke again, but _____ didn’t help.
A. he B. it
C. which D. as
B
it 指前面提到的情况。由于句中用了并列连词 but，所以不能选C。当然，若去掉空格前的but，则可选C。