责任产生于社会关系中的[ ]
A．相互理解
B．相互尊重
C．相互帮助
D．相互承诺
答案：D
—How many students are there in the room?
—There aren't _____.
A. some
B. any
C. one
D. it
风湿性心脏病二尖瓣狭窄时，可以引起哪些器官的淤血性改变？
