硝酸甘油、β受体阻滞剂和钙通道阻滞剂治疗心绞痛的共有作用是()。
A.减慢心率
B.减弱心肌收缩力
C.解除冠脉痉挛
D.降低心肌耗氧量
参考答案:D
For each blank, choose the best answer from the four choices and write down on the answer sheet. Web browser is simply a terminal emulator, designed to display text on a screen. The two essential differences between an ordinary terminal emulator and a Web browser are that the browser knows how to deal with (71) , and that it has a mechanism for (72) graphical files. Display text, display graphics, and (73) hyperlinks—there’s 99 percent of the (74) value. That’s not to say that the manufacturers didn’t go all-out to attach a hyperactive efflorescence of useless capabilities onto their browsers. Remember when media channels in the browser were a big deal, instead of the clutter you can’t wait to delete from your favorites of bookmarks menu Remember when client-side Java applets were supposed to become the preferred (75) for application development Remember frames and all their nasty side effects
A. displayingB. illustrating C. drawingD. writing
离心式泵与风机的基本结构由哪几部分组成?每部分的基本功能是什么?