有关下面四个国家地理特征的叙述，正确的是（ ）

如图所示为某兴趣小组为学校办公楼空调设计的自动控制装置，R是热敏电阻，其阻值随温度变化关系如下表所示．已知继电器的线圈电阻R₀=15Ω，左边电源电压为6V恒定不变．当继电器线圈中的电流大于或等于15mA时，继电器的衔铁被吸合，右边的空调电路正常工作．

（1）请简要说明该自动控制装置的工作原理．

（2）计算说明该空调的启动温度是多少？

（3）为了节省电能，将空调启动温度设定为25℃，控制电路中需要再串联多大的电阻？

（4）改变控制电路的电阻可以给空调设定不同的启动温度，除此之外，请你再提出一种方便可行的调节方案．

    You might want to think twice before purchasing____(conventional) grown strawberries or spinach(菠菜). According to a new report from the Environmental Working Group(EWG), these foods are the most likely____(pollute) with the pesticide.

    Even low levels of pesticide exposure can be harmful to infants, babies and young children,____parents and caregivers should take measures to lower children's exposures____pesticides while still____(feed) them diets rich in healthy fruits and vegetables.

    Just last year, the red berry knocked apples and____(hold) the title of the most polluted. The pesticide increased in strawberries because of out-of-season demand. The most polluted strawberry had traces of 20____(vary) pesticides.

    Also moving up on____list this year is spinach. Spinach jumps from the____(eight) to the second most polluted product. The study finds spinach samples contain more pesticides by weight than all other produce____(test). In high doses, it can cause damage to the nervous system.