A. It is a cake.
B. Apple juice, please.
C. They are purple.
D. No. It's hard.
E. Yes, it is.
① ____ Touch this. Is it soft?
② ____ Can I help you?
③ ____ What is it?
④ ____ What colour are they?
⑤____ Is it a pencil case?
氢氧燃料电池用于航天飞船,电极反应产生的水,经冷凝后可作为航天员的饮用水,其电极反应如下:①2H2+4OH﹣-4e﹣=4H2O,②O2+2H2O+4e﹣=4OH﹣ 当得到1.8L饮用水时,电池内转移的电子数约为( )
解释下列词语的含义。
障碍: ____ 。
毫不在乎:____ 。