After the snowstorm, mailboxes in the community were covered by snow, or _______, or lying on the ground.

A．breaking

B．being broken

C．having broken

D．broken

下列哪项不是慢支并发肺气肿的X线表现（）

A.两肺纹理增粗紊乱

B.早期可无异常

C.两肺多发性空洞

D.两肺透亮度增加

E.横膈低平