基床以下路堤应选用（）和（）、（）填料。
参考答案：A、B组填料；C组碎石类；砾石类
电除尘器停运后，振打机构可以随时停运。（）
_____ for his mistake, the little boy could not but _____to his teacher that he was wrong.
A．Blaming; to admit
B．Blamed; admit
C．To blame; admitted
D．To be blamed; admitting
