如图1所示，底面积为2×10^-2米²的薄壁轻质圆柱形容器放在水平地面上．容器内水的深度为0.1米．

①求水对容器底部的压强ρ_水．

②求容器中水的质量m_水．

③如图2所示，将容器放在面积为4×10^-2米²的正方形木板中央，并置于水平地面上．现有物体A、B（其密度、体积的关系如表所示），请选择一个，当把物体浸没在容器内水中后（水不会溢出），可使水对容器底部压强的增加量△ρ_水与水平地面受到的压强增加量△ρ_地的比值最大．

（a）选择______物体（选填“A”或“B”）．

（b）求△ρ_水与△ρ_地的最大比值．

Since minors should not smoke, the proposed law prohibiting cigarette sales to minors is reasonable. However, the proposed ban on cigarette vending machines is like installing a roadblock to apprehend the one person in a hundred who drives without a license. A roadblock stops everyone, not just those who break the law.
The answer to which of the following questions would be most important in evaluating the objection above to a ban on cigarette vending machines

A．Do cigarette vending machines malfunction more frequently than do food vending machines

B．Are there current laws that prohibit the sale to minors of materials intended only for adults

C．Would an increase in taxes on cigarette sales help deter minors from purchasing cigarettes

D．Would a ban on cigarette vending machines inconvenience a significant number of cigarette-buying adults

E．(E) Are items more expensive when sold from a vending machine than when sold in retail stores