下列物质属于非电解质的是（ ）
A．NH3
B．（NH4）2SO4
C．Cl2
D．CH3COOH
答案：A
His father ________ for a week.
A．died
B．will die
C．has been died
D．has been dead
相对浊音区能够反映心脏真实大小。
