临床上评价舒张功能的金标准是（）
A.心导管所测参数
B.左房室瓣口血流频谱
C.左房室瓣环运动速度
D.等容舒张时间
E.肺静脉频谱
参考答案：A
ASCII码其实就是
A．美国标准信息交换码
B．国际标准信息交换码
C．欧洲标准信息交换码
D．以上都不是
If his parents are convinced ____the fact that his son always focuses his mind his study.
A．of; on
B．of; at
C．by; to
D．on; at
