急性心包炎
A．ST段弓背向上抬高B．ST段弓背向下抬高C．ST段呈水平型下移D．ST段呈上斜型下移E．ST-T呈鱼钩样改变
参考答案：B
Sugar is usually sold by _______ weight, and eggs are sometimes sold by ______ dozen. [ ]
A. / , the
B. / , a
C. the, a
D. the, the
建立安全环境的3个重要组成部分分别是威严的法律、先进的技术和______。
