Lucy ________ guitar lessons every three weeks in the past three years, but now she is considering she'll make it every other week.

A．is having　

B．had had

C．had　

D．has been having

利用水的蒸发原理测定大气相对湿度，其具体的测试仪器有（）。

A.自记式温度计

B.吸气式阿斯曼湿度计

C.露点仪

D.电阻式湿度传感器