问题 单项选择题 B1型题

LASIK术后感染性角膜炎的危险因素为()。

A.术前或术中角膜上皮损伤

B.干眼症伴持续性角膜上皮缺损

C.术后早期患者用力揉眼

D.A、B、C都可出现

E.A、B、C都不可能

答案

参考答案:B

解析:1.LASIK术后感染性角膜炎的危险因素为:疱疹性角膜炎;眼附属器感染,如睑缘炎、泪囊炎;睑内翻倒睫;长期佩戴角膜接触镜;干眼症伴持续性角膜上皮缺损;外伤后角膜瓣移位或再次掀开角膜瓣治疗;HIV感染;其他因素,如术中不注意无菌操作,使用受污染的滴眼液或器械消毒不严格,可造成同一批手术患者集体感染,术后局部长时间使用皮质激素滴眼液。2.LASIK术后角膜瓣皱褶的可能原因为:角膜瓣偏薄或水肿,角膜瓣在水肿消退后遗留皱褶,多呈"篮缝样"或"龟背样";高度近视矫正术后由于中央角膜显著变平,角膜瓣与角膜床贴合不良更容易产生角膜瓣皱褶;术中过度按压角膜瓣或擦除水液时方向不正确;术中角膜瓣干燥不够充分;撤除开睑器时接触角膜瓣;术后早期患者用力揉眼。3.LASIK术后角膜瓣下上皮细胞内生的可能原因为:术前或术中角膜上皮损伤;术后角膜瓣下炎症反应;再次LASIK手术。4.弥漫性层间角膜炎的可能诱因为角膜层间异物存留,包括:手套上的滑石粉、刀具上的金属碎屑、润滑油、细菌内毒素、激光切削后产生的物质、睑板腺分泌物及消毒液等。当角膜层间有残留物如黏液、白细胞、上皮细胞、金属颗粒、滑石粉或角膜瓣过薄、破损时,角膜细胞被激活的持续时间延长,愈合反应加重。在LASIK术后伤口愈合过程中,角膜组织内产生一些炎症介质,如蛋白溶解酶、前列腺素、过氧化氢自由基、羟基及细胞因子等坷能导致角膜层间炎症反应甚至角膜组织自溶。

阅读理解

阅读理解。

     The Fourth "21th Century Cup" National English Speaking Competition is to be held in Shanghai.

     Organizers: China Daily and Shanghai Broadcasting Network.

     Co-ordinator: China University English Speaking Association (CUESA).

     Co-sponsors (联办单位): English Speaking Union ( ESU), Lotus Software (China) Co. Ltd., Times

Publishing Group of Singapore, Hilton Shanghai, Pearson Education, Foreign Language Teaching & Research

Press.

     Date: March 26 (Friday), 1999.

     Place: Hilton Shanghai.

     Competition Format (形式): Each student will present a prepared speech on the given topic, followed by

a three-minute off-hand speech and a three-minute question and answer period with the judges.

     Prepared speech period: six minutes.

     Q&A period: three minutes.

     Speech topic: People and Nature: In search of harmony (和谐) in a new age + your personal opinion.

(Topic for the off-hand speech will be given on the day of competition.)

     Prizes: Besides books and certificates (证书), the top two winners will be offered scholarships (奖学金)

to travel to the annual international English-speaking competition which will be held by the English Speaking

Union in London in May, 1999. The third and fourth place winners will be offered a study trip to Singapore,

sponsored by the Times Publishing Group. The fifth through tenth place winners will be offered cash prizes.

All the competitors will receive certificates from the English Speaking Union and book prizes provided by

Pearson Education and Foreign Language Teaching & Research Press. The teachers of the top winners will

also receive a one-year membership to the International Association of Teachers of English as a Foreign

Language (IATEFL).

1. The main purpose of this passage is ____.

A. to invite you to take part in the competition

B. to tell you some information of the competition

C. to help to improve your spoken English

D. to show you how to win the competition

2. Which of the following is NOT mentioned about the Shanghai English Speaking Competition?

A. Where and when it will take place.

B. Its program.

C. What each winner will be offered.

D. The number of its competitors.

3. Suppose you get the sixth place, you'll ____.

 A. travel to London for free

B. become a one-year member of IATEFL

C. get some money, some books and a certificate

D. get a chance to study in Singapore

4. An "off-hand speech" is ____.

A. a speech not longer than three minutes

B. a speech without preparation

C. a speech with a piece of paper in hand

D. a speech which is well prepared

单项选择题