—Must I let my mother know it?—.You can keep it as a secret.A. Yes you must B. No you mu

问题补充：

—Must I let my mother know it?

—.You can keep it as a secret.

A. Yes, you must B. No, you mustn’t C. No, you needn’t

答案：

解析： Must I…?肯定回答Yes, you must，否定回答No, you needn’t。根据句意：我必须让妈妈知道吗？-----，你可以把它当作一个秘密，故选C。