搜题请搜索小程序“爱下问搜题”
问题 单项选择题

动物发生肺炎初期，其心音变化表现为______。

A．第一心音增强
B．第二心音增强
C．第一、二心音同时增强
D．第一、二心音同时减弱 E．第二心音减弱、甚至消失

答案

参考答案：B

填空题

The teenage year from 13 to 19 were the most difficult time for me . They were also the best and worse years in my life . At the first, I thought I knew everything and could make decisions by yourself. However, my parents didn’t seem to think such. They always tell me what to do and how to do it. At one time , I even felt my parents couldn’t understand me so I hoped I could be freely from them. I showed them I was independent by wear strange clothes. Now I am leaving home to college. At last, I will be on my own, but I still want to have my parents to turn to whenever need help.

7（）
查看答案
问答题 简答题

简述抽样调查法。
查看答案