电凝止血的原理是______________________。
参考答案:电热作用使血液凝结
Directions: Water is probably most important for life, but we are going to face a shortage of water. There has been a discussion recently on this issue in a newspaper. Write an essay to the newspaper to express your views. Your essay should make full use of the following statistics and should cover these points: (1) the current situation of water in China; (2) the cause of the problem; (3) your suggestions of solution. You should write about 200 words.
典型心绞痛病人舌下含化硝酸甘油后,疼痛消失时间多在()。
A.几秒钟以内
B.1~2分钟
C.10~15分钟
D.20分钟左右
E.30分钟以上