气体交换的场所是
A．三焦B．肺C．肾D．脾E．肝
参考答案：B
Tom took the police to the spot ________ the accident happened.
A．which
B．that
C．where
D．when
将Zn加入到含有Fe2+，Cu2+，Ag+，Al3+等离子的溶液中，最先被置换出来的单质是[ ]
A．Fe
B．Cu
C．Ag
D．Al
