Semiconductor thermistor is a kind of semiconductor device whose resistance changes sensitively with temperature. According to this characteristic, it can be used to generate electricity.

(1): Draw the following figure according to the tracing method:

(2) According to the θ-U image, the voltmeter readings corresponding to the four temperature values of 20℃, 40℃, 60℃ and 80℃ are: 20℃-1.83v; 40℃- 1.08v； 60℃-0.62v； 80℃-0.42 V According to the data on the chart, the reading range of the voltmeter is within the range of "0-3V", so the range of "0-3V" is selected.

(3): According to the circuit diagram, we can get: u? 0=U+U？ r？ 0,

Is the current through the circuit I=U? r？ 0R？ 0,

The thermistor is:? r？ t=UI，

Synthesize the above solutions: r? t=UR？ 0U？ 0? u，

As can be seen from the image, the voltmeter voltage at 20°C is U= 1.83V, which is obtained by substituting the above formula: r? t = 0.36kΩ

So the answer is: (1) as shown in the figure.

(2) "0-3v" range

(3)0.36kω，R？ t=UR？ 0U？ 0? U