确诊二尖瓣狭窄最可靠的辅助检查方法是
A．X线检查
B．心电图检查
C．超声心动图检查
D．心音图检查
E．心导管检查
参考答案：C
Please write to ______ as soon as you get to London.[ ]
A. I
B. my
C. me
D. mine
HF、H2O、CH4、SiH4四种气态氢化物按稳定性由弱到强排列正确的是（ ）
A．CH4＜H2O＜HF＜SiH4
B．SiH4＜HF＜CH4＜H2O
C．SiH4＜CH4＜H2O＜HF
D．H2O＜CH4＜HF＜SiH4
