单人对1个2岁小孩进行现场心肺复苏．心脏按压与人工呼吸的比率是（）
A.5：1
B.5：2
C.15：1
D.15：2
E.30：2
参考答案：E
可引起巨幼红细胞性贫血的药物是
A．氯喹B．奎宁C．伯氨喹D．乙胺嘧啶E．甲氟喹
______ is particularly interested in the relationships between sentences and the contexts and situations in which they are used.
