English grammar

1. this sentence is correct.
2. this sentence is wrong (after [does] use [have] base form)
3. this sentence is correct. (in past tense)
4. this sentence is correct. (in present tense)

2008-01-13 20:59:12 補充：
a nap 小睡 = a short sleep, so you either use [a short sleep] or [a nap] no need to use [a short nap]1. 打盹兒,午睡[C]She took a nap every afternoon.她每天下午小睡一會兒。vi.1. 打盹,小睡The old man napped on the porch.那位老人在走廊上打盹兒。usually = often (same meaning)

1 When does John often have dreams?
TO BE CORRECTED AS---- When does John usually have dreams?

2 When does John often has dreams?
TO BE CORRECTED AS----- How often does John have dreams?

3 John often had a short sleep in the afternoon.
IT IS O.K. WHEN IT WAS IN THE PAST.

4 John often has a short sleep in the afternoon.
IT IS O.K. WHEN IT DENOTES AN USUAL PRACTICE.

1. correct

2. Incorrect
does 後的verb 用bare infinitive
When does John often (HAVE) dreams?

3.(a) often 表達一些重覆的動作或習慣, 需要present tense
(b) a short sleep 建議改成 (take) a nap = 小睡
John often (TAKES A NAP) in the afternoon.

4. 同上的 3(b)
John often (TAKES A NAP) in the afternoon.

1. When does John usually have dreams?
2. Incorrect
3. John often had a short nap in the afternoon.
3. John often has a short nap in the afternoon.