消防排烟机的种类很多,主要有()。
A.手动排烟机和机动排烟机
B.电动排烟机和机动排烟机
C.机动排烟机和气动排烟机
D.气动排烟机
参考答案:B
检查胆系疾病的首选方法是()
A.B超
B.CT
C.经内镜逆行性胰胆管造影
D.口服胆囊造影
E.经皮肝穿刺胆道造影
She is a crazy fan of this singer.______ she listens to his songs hundreds of times, she will never get tired.[ ]
A. If
B. As long as
C. Unless
D. Even if