I _____his letter for a week. [ ]
A. heard from
B. have received
C. have had
D. have got
答案:C
砂姜黑土属于()。
A.淋溶土纲
B.干旱土纲
C.半水成土纲
D.水成土纲
下列哪些是护理诊断的结构要素()
A.结果
B.措施
C.健康问题
D.症状和体征
E.原因