辐射防护的材料应采用原子序数较低的物质作第一层。()
参考答案:对
—I hear Jim is going to _________ at the school meeting.
—Do you know what he is going to ________ ?
A. say, talk
B. say , speak
C. speak, say
D. talk , speak
患者,男性,以“气短、咳嗽、胸痛4个月”来诊。考虑存在下列哪种疾病时,超声检查最适宜
A.自发性气胸
B.肺结核
C.胸膜炎
D.肺恶性肿瘤
E.包裹性积液定位诊断