治疗支气管哮喘最有效的药物是（）。
A．沙丁胺醇
B．布地奈得
C．色甘酸钠
D．曲尼司特
E．氨茶碱
参考答案：B
马胸部叩诊呈现水平浊音是______的特征( )。
A．大叶性肺炎
B．肺水肿
C．渗出性胸膜炎
D．心包积水
E．肺充血和肺水肿
Loulan is believed ____ by sandstorms from AD 200 to AD 400.
A．to be gradually covered over
B．to have been gradually covered over
C．being gradually covered over
D．having been gradually covered over
