—Do you like history?

—Yes, it's ______.        [ ]

A. interesting  

B. boring    

C. different    

D. difficult

门扇应有足够的结构刚度，刚度试验载荷应满足门扇应有足够的结构刚度，刚度试验载荷应满足（）受力要求。

A.1.5kPa

B.2kPa

C.2.5kPa

D.3kPa