Cars do us some health problems---in fact far more serious_____ than mobile phones do.   [ ]

A. it        

B. the one    

C. those    

D. ones

肋形楼盖荷载传递路线依次为( )。

A．主梁→次梁→板→柱或墙

B．板→宅梁→次梁→柱或墙

C．板→次梁→主梁→柱或墙

D．次梁→板→主梁→柱或墙