‌乘除运算的偶然误差传递规律为：积、商的相对标准偏差的平方等于各测量值相对标准偏差的平方和。（）​

单项选择题胸骨右缘第2肋间特别是胸骨左缘3,4肋间听到舒张期叹气样杂音,并向心尖部传导见于 A、二尖瓣关闭不全 B、二尖瓣狭窄 C、主动脉瓣狭窄 D、主动脉瓣关闭不全 E、动脉导管未闭

单项选择题Before putting forward your question, you need to show your appreciation to the speaker and make a positive comment on his speech. A、正确 B、错误