必须凭执业医师或执业助理医师处方才可调配、购买并在医师指导下使用的药品是( )A． 发布时间：2018-06-28 14:19 │ 来源：www.tikuol.com 题型：单项选择题 问题： 必须凭执业医师或执业助理医师处方才可调配、购买并在医师指导下使用的药品是( )A．柜台发售药品B．处方药C．非处方药D．OTCE．中成药
题型：单项选择题 A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out a short burst of radio waves: Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar," in fact, gets its name from the term "radio detection and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.What is the main topic of this passage A．The nature of radar.B．Types of ranging.C．Alternatives to radars.D．History of radar. 查看答案
题型：单项选择题 关于HFRSV的免疫性，下列哪项是正确的A．机体主要依赖于IgM的保护作用B．机体主要依赖于IgM、IgG的保护作用C．隐性感染形成的免疫力持久D．病后免疫力不牢固E．机体主要依赖于SIgA的保护作用 查看答案
题型：单项选择题 下列关于增感屏使用的叙述中，哪种是正确的？（）A、用荧光增感屏进行X射线照相时，曝光时间可以显著缩短，但底片的像质较差B、荧光增感屏的增感作用不如铅箔增感屏C、用铅箔增感屏时，若X射线管的管电压太高，会产生磷光现象D、用荧光增感屏进行X射线照相时，曝光时间虽然较长，但底片的像质较好 查看答案