Only _______ to borrow magazines from the reading-room.

A．are the teachers allowed

B．the teachers are allowed

C．are allowed the teachers

D．did the teachers be allowed

P波与QRS波群完全无关，P波频率>QRS频率见于（）

A.一度房室传导阻滞

B.二度Ⅰ型房室传导阻滞

C.二度Ⅱ型房室传导阻滞

D.三度房室传导阻滞

E.室内传导阻滞