测金属电阻率实验

①测长度时，金属丝的起点、终点位置如图（a），则长度为：         cm

②用螺旋测微器测金属丝直径，示数如图（b），则直径为：         mm

③用多用表“Ω×1”挡估测其电阻，示数如图（c），则阻值为：        Ω

④在图d中完成实物连线

⑤闭合开关前应将滑动变阻器的滑片P移至最         （填“左”或“右”）端。

---I had practiced my spoken English, but still failed in the oral test.

---Don’t be discouraged. _____ and you will surely pass it.

A．Make a bit more effort

B．To make a bit more

C．Making a bit more effort

D．If you make a bit more effort