①②③④四种金属片两两相连浸入稀硫酸中都可组成原电池，①②相连时，外电路电流从①流向②；①③相连时，③为正极；②④相连时，④上有气泡逸出；③④相连时，③的质量减少。据此判断这四种金属活动性由大到小的顺序是（ ）
| A．①③②④ | B．①③④② | C．②①③④ | D．③①②④ |
相关试题
The CDs are on sale! Buy one and you get ______ completely free. 
| A． | other | B． | others | C． | one | D． | ones |
I’m sure that your letter will get______ attention. They know you’re waiting for the reply. 
| A．continued | B．immediate | C．careful | D．general |
All the dishes in this menu, ______ otherwise stated, will serve two to three people. 
| A．as | B．if | C．though | D．unless |
The children loved their day trip, and they enjoyed the horse ride ______.
| A．most | B．more | C．less | D．little |
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