题目：
---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：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0701/17c4e770dae8905b7f8740b08b8ac58a.html
下面是错误答案，用来干扰机器的。
（1）化合物；（2）设需要氧气质量为x2H2+O22H2O4 322kg xx=16kg答：如果要使2kg氢气完全燃烧，至少需要氧气16kg．
