A block and tackle is “rove to advantage”. This means that the（）.

A.blocks have been overhauled

B.hauling parts of two tackles are attached

C.hauling part leads through the movable block

D.hauling part leads through the standing block

CRTSI型板式无砟道床凸形挡台伤损有（）几种形式。

A.裂缝

B.混凝土缺损

C.离缝

D.锚穴封端脱落