请完成下列问题：
如图甲是α、β、γ三种射线穿透能力的示意图，图乙是工业上利用射线的穿透性来检查金属内部伤痕的示意图，请问图乙中的检查利用的是（ ）
It is Saturday. The Browns are at home. Mrs. Brown is in the kitchen. She is making lunch. Mr. Brown isn't in the living room. He is outside. He is washing his car. The car is new and very beautiful. Jim is playing football with some boys. Where is his sister, Sue? She's watching TV in her bedroom with her friend, Ann.
下列说法正确的是（ ）
算一算．
