What's the matter, Miss Lin?

I am having trouble _____ out who has taken away my book on this desk.[ ]

A. find

B. to find

C. finding

D. found

如图是某同学制作的简易净水器，下列说法不正确的是（　　）

A．装置中小卵石、石英沙起过滤作用

B．硬水通过该装置净化后得到的水是软水

C．用肥皂水可以区别净水后的水是硬水，还是软水

D．长期饮用硬水对健康不利