问题 单项选择题

某患者,左眼无痛性视力下降半年就诊,检查左眼视力为眼前手动,眼球前段无异常,眼底检查见颞上方一3PD大小马蹄形裂孔,孔边卷曲,后极部视网膜表面增殖膜形成并收缩致全视网膜隆起,眼球右转才能见到视盘。按照国际视网膜学会1983年分类,该患者应属于()

A.PVR-C1级

B.PVR-C2级

C.PVR-C3级

D.PVR-D1级

E.PVR-D2级

答案

参考答案:E

解析:按照1983年标准,PVR被分为A、B、C、D四级,A级为玻璃体内有色素颗粒和混浊。B级视网膜皱褶、裂孔卷边、血管扭曲抬高。C级为全层的视网膜固定皱褶,其中又按照受累象限多少分:C1~C3分别表示病变位于1~3各象限。D级表示固定皱褶累及全视网膜。其中D1指视网膜脱离为宽漏洞(视盘尚可以直接见到),D2指窄漏斗(漏斗口<45°范围内,眼球转动仍可见视盘),D3则为看不见视盘的闭合漏斗。本病例全视网膜被增殖膜收缩牵拉而隆起,转动后才能见到视盘,属于PVR-D2级,因此应选择答案E。

单项选择题

Questions 58 to 62 are based on the following passage: ( 10分)  According to the airline industry statistics, almost 90% of airline accidents are survivable or partially survivable. But passengers can increase their chances of survival by learning and following certain tips. Experts say that you should read and listen to safety instructions before takeoff and ask questions if you have uncertainties. You should fasten your seat belt low on your hips as tightly as possible. Of course, you should also know how the release mechanism of your belt operates. During takeoffs and landings you are advised to keep your feet flat on the floor. Before takeoff you should locate the nearest exit and an alternative exit and count the rows of seats between you and the exits so that you can find them in the dark if necessary.  In the event that you are forewarned of a possible accident, you should put your hands on your ankles and keep your head down until the plane comes to a complete stop. If smoke is present in the cabin, you should keep your head low and cover your face with napkins, towels, or clothing. If possible, wet these for added protection against smoke inhalation. To evacuate as quickly as possible, follow crew commands and do not take personal belongings with you. Do not jump on escape slides before they are fully inflated, and when you jump, do so with your arms and legs extended in front of you. When you get to the ground, you should move away from the plane as quickly as possible, and never smoke near the wreckage.

Airline passengers are specifically told NOT to __

A.carry personal belongings in an emergency

B.locate the nearest exit

C.ask questions about safety during the flight

D.jump in any circumstances

填空题