题目

Are some people born clever and others born stupid? Or is intelligence developed by our environment and our experiences? Strangely enough, the answer to both these questions is yes．To some extent our intelligence is given us at birth, and no amount of special education can make a genius（天才）out of a child born with low intelligence．On the other hand, a child who lives in a boring environment will develop his / her intelligence less than one who lives in rich and varied surroundings．Thus the limits of a person’s intelligence are fixed at birth, but whether or not he / she reaches在“学习使用滑动变阻器”的实验中（1）连接实物时，开关闭合之前应当将滑片P应移至____位置．（2）开始实验后，甲同学发现无论怎样移动滑片P，灯的亮度都不发生变化，而且一直很暗，这可能是____；丙同学缓慢移动滑片P时，看到灯忽亮忽熄，这可能是 ．