影响第一心音强度变化的因素不包括（）
A.心肌收缩力
B.心室充盈度
C.瓣膜弹性
D.瓣膜位置
E.心室壁厚度
参考答案：E
Her father works as a _________ in a hotel and her mother a _________ in a private company.
A．cooker, typewriter
B．cook, typist
C．cooker, typist
D．cook, typewriter
