问题 单项选择题 A1/A2型题

有关肺隔离症,正确的是()

A.多以咳嗽、胸痛就诊

B.均有独立的脏层胸膜包裹

C.肺叶外型不易引起感染

D.一般与支气管相通

E.其血供来自支气管动脉

答案

参考答案:C

解析:肺隔离症是一类发育异常,为胚胎时期一部分肺组织和正常的肺分离单独发育,与正常支气管树不相通,无呼吸功能,其血供来自体循环(胸主动脉、腹主动脉,或锁骨下动脉的分支),引流静脉经肺静脉、下腔静脉或奇静脉回流。可分为肺叶内型及肺叶外型。肺叶内型肺隔离症病变区与邻近正常肺组织由同一脏层胸膜所包裹,隔离的肺组织易于感染,感染时易与支气管相通。最多发生在肺下叶的后基底段,左侧多于右侧。肺叶外型肺隔离症为副肺叶或肺段,由单独的脏层胸膜所包裹,病变多为肺组织块,不易引起感染。多数患者无症状,于体检时偶然发现。

单项选择题

A total of 4.6 million digital televisions have been sold, and the sales of HDTV sets have quadrupled since last year. Consumers have bought HDTVs to play their DVDs and to have clearer pictures and wide screens. Only a small percentage of the people who have purchased HDTVs, however, have actually ^hooked their TVs up# to receive high-definition television digital signals. Perhaps television viewers are having trouble keeping up with the changes in technology. Even the manufacturers of HDTVs, like Mitsubishi, Thomson Multimedia, Sony, and Samsung seem to have a tough time learning how to make their sets work with the various digital TV formats because little standardization has been required or implemented in the industry.Some of the HDTVs weigh over 200 lbs., and a variety of retailers offer a delivery service to the buyer’’s home to help install the heavy sets. This is known as a white-glove service and usually comes with an extra fee. After HDTV purchasers get their sets home and hook them up, they will still need to work to get the digital signals to their systems. Most of the industry’’s cable providers do not yet offer high-definition programing, and only about 15% of commercial television stations have switched over to even the lowest improved digital pictures. Worse yet, viewers may need to install antenna before they can even get the digital signals to their new HDTV sets. Another frustration for home-theater seekers is that the current HDTV sets allow owners only to watch high-definition programs, not to record them.

According to the first sentence, the sales of HDTV sets since last year, by the time when this article was written, had reached________.

A.4.6 million

B.9.2 million

C.18.4 million

D.I do not know how many

选择题