The rhetorical question: “能……吗？”
In Chinese, the structure “能……吗？” (néng... ma?) is used to form a rhetorical question. It does not expect a direct answer, but rather strongly emphasizes a statement. The actual meaning is opposite to the grammatical form:
Positive Form (能 + Verb + 吗？) → Expresses a Negative Meaning ("How can you...?" / "Is it possible to...?").
Negative Form (能不 + Verb/Adjective + 吗？) → Expresses a Positive Meaning ("How could you not...?" / "Of course...").
Dialogue Examples
Example 1 (Positive Form → Negative Meaning)
为什么我的汉语学得不好？
你不做作业，也不练习，能学好吗？
Actual meaning: 不能学好 — You cannot learn it well!
Example 2 (Negative Form → Positive Meaning)
你看，我这么胖，怎么办呢？
你每天晚上吃了饭就睡觉，也不出去走走，能不胖吗？
Actual meaning: 会胖 — You will definitely gain weight!
Quick Summary
能好吗？
能不好吗？