综合布线系统分为（）设计类型。
A.混合型
B.基本型
C.增强型
D.综合型
参考答案：B, C, D
下列离子方程式中，正确的是（ ）
A．稀硫酸滴在铜片上：Cu + 2H+= Cu2++ H2↑
B．氧化镁与稀盐酸混合：MgO + 2H+= Mg2++ H2O
C．铜片插入硝酸银溶液中：Cu + Ag+= Cu2++ Ag
D．铁与稀硫酸反应 2 Fe + 6H+ = 2Fe3+ + 3H2↑
Ships traveling in the North Atlantic during the winter must be constantly watchful to avoid icebergs, large masses of ice ______ only one-ninth is visible above water.
A．so that
B．in that
C．which
D．of which
