纸质滤芯优点是（）。
A、能反复使用
B、不需定期更换
C、吸附杂质能力强
D、滤清效率高
E、清晰方便
参考答案：C, D
We are satisfied with his job in our company. Everything goes better now than when he his work here.
A．has started
B．would start
C．started
D．had started
属于五行之“金”的是（）。
A.青
B.赤
C.黄
D.白
E.黑
