Without proper lessons, you could ____ a lot of bad habits when playing the piano.

A．give up

B．catch up

C．keep up

D．pick up

关于石膏，下列哪些是正确的（）

A.苦，甘，寒

B.善清泄气分实热和肺胃实火

C.煅后外用收敛之中又兼清热之性

D.治气分高热和肺胃实火之要药

E.又解肌透热，热去则烦除津生渴止