问题补充：
---Do you know after Japanese earthquake and tsunami（海啸）?
--- Sure. For three weeks.
A. when did the dog float(漂浮) on the sea
B. when the dog floated on the sea
C. how long did the dog float on the sea
D. how long the dog floated on the sea
答案：
A. when did the dog float(漂浮) on the sea
B. when the dog floated on the sea
C. how long did the dog float on the sea
(答案→)D. how long the dog floated on the sea
解析：根据特殊疑问句作为宾语从句，要注意使用陈述句语序，故选D
