《入境货物报检单》的“索赔有效期至”一栏应填写索赔有效期的天数。
参考答案：错
At night, plants _________carbon dioxide and at the same time _________oxygen. So, we may put some in our bedrooms to purify the air.
A．take in, give out
B．take up, give off
C．take in, give in
D．take off, give up
下列哪些属于活塞空气压缩机实际工作循环过程（）
A.压缩、排气
B.膨胀、排气
C.循环、压缩
