Question

—Can you tell me ________ ?

—Once a month．

1. A.
   how often do you visit him
2. B.
   how often you visit him
3. C.
   how long you visit him
4. D.
   how many times do you visit him

Answer 1

B
从答语Once a month判断是问频率的，应该用how often, 因此要从A和B里选，要先的部分在问句中作宾语从句，应该是“how often+陈述句”。