【例1】风向标模型(第二册第3课)。用纸板(?)薄金属板做尾翼,细木棒做指针,固定在同一根竖立的轴上,然后将竖立的轴插入支座的套筒内,如图1所示。套筒的底(?)放一颗钢珠.用(?)支托风向标竖立(?)轴,使风向标能灵活转动。此外,(?)图1的指针上,还要套一螺丝帽或(?)上几层牙膏袋皮(?)平衡重物,使指(?)和尾翼能够平衡起来。支座上用色彩鲜艳的油漆写上“东”、“南”、“西”、“北”四个字。教学(?),将电风扇的风从不同方位吹向风向标,风向标的 [Example 1] Wind vane model (Section 2 of Book 2). Use a cardboard (?) thin metal plate as the fin, a fine wooden bar as the pointer, and fix it on the same vertical shaft. Then insert the vertical shaft into the sleeve of the holder, as shown in Figure 1. Put a steel ball at the bottom of the sleeve (?). Use a (?) support wind vane to erect the (?) axis so that the wind vane can rotate flexibly. In addition, the (?) pointer in Figure 1, but also put a screw cap or (?) a few layers of toothpaste bags (?) balance weights, so that the fingers (?) And the tail can be balanced. On the support, the words “East,” “South,” “West,” and “North” were written in brightly colored paint. Teaching (?), blowing the fan’s wind from different positions to the wind vane, wind vane