端角反射的每次反射过程都遵循超声波的()。
A、反射定律
B、折射定律
C、入射定律
D、反转换定律
参考答案:A
More and more dangerous work _____________ by robots in ten years.
A is finished B was finished
C will be finished D has been finished
坚果的营养特点是富含矿物质和B.族维生素,能量高,水分少。