心脏超声检查最常用的探头是
A．线阵探头B．凸阵探头C．TEE探头D．相控阵探头E．矩阵探头
参考答案：D
一台电脑原价5000元，现在打八折出售，现价每台______元．
I can't believe what he says because he is _______ changing his mind. .
A．regularly
B．steadily
C．suddenly
D．constantly
