头先露中最常见的是（）
A.枕先露
B.前囟先露
C.额先露
D.面先露
E.肩先露
参考答案：A
She showed the visitors around the museum, the construction _____ had taken more than three years.
A．for which
B．with which
C．of which
D．to which
曲柄连杆机构和配气机构的异响与发动机工作循环没关系。（）
