转K6型转向架系铸钢（）式货车转向架。
参考答案：三大件
________ the difficult things happened when I can't adjust myself? [ ]
A. What about
B. What with
C. What if
D. What for
如图，将周长为8的△ABC沿BC方向平移1个单位得到△DEF，则四边形ABFD的周长为
A．6
B．8
C．10
D．12
