We all think it is Mr Wang as well as his parents that _______ for his son’s bad performance at school.

A．are to blame

B．is to be blamed

C．are to be blamed

D．is to blame

大气道阻塞时（）。

A.呼气费力

B.呼气时伴有广泛哮鸣音

C.常伴有湿啰音

D.常见于支气管哮喘

E.重者出现吸气时"三凹征"