题目

Popeye the Sailor first became a popular cartoon in the 1930s.The sailor in that cartoon ate lots of spinach to make him strong.People watched him, and they began to buy and eat a lot more spinach.Popeye helped sell 33 percent more spinach than before!Spinach became a necessary part of many people’s diets.Even some children who hated the taste began to eat the vegetable. Many people thought that the iron in spinach made Popeye strong, but this is not true.Spinach does not have any more iron than any other green vegetable. People only thought spinach had a lot of iron because the people who s6．以下说法中正确的是（　　）A．照相机镜头表面的镀膜是光的偏振现象的应用B．β衰变所放出的电子来自原子核外C．γ射线是一种波长很短的电磁波D．放射性元素的半衰期随温度的升高而变短