People cannot but feel _____, for they simply cannot understand how he could have made such a stupid mistake.

A．puzzled

B．delighted

C．comforted

D．inspired

混凝土管和钢筋混凝土管的抗酸、碱侵蚀及抗渗性能都非常好，且管节较长、接头少，广泛用于排水管道工程。