简单反射生来就会，叫做（）反射
参考答案：非条件
—Sorry, I have no time to help you carry the water. I have to look after my sister.
—____[ ]
A. Is it?
B. You're welcome.
C. Thank you.
D. Thank you all the same.
目前国家、机关上常用的正式文件纸张是（）
A、16开
B、A4
C、B5
