问题
选择题
Liu Xiang can't attend the Political Consultative Conferences ____ in Beijing due to training. [ ]
A. to hold
B. held
C. to be held
D. being held
答案
答案：D
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Liu Xiang can't attend the Political Consultative Conferences ____ in Beijing due to training. [ ]
A. to hold
B. held
C. to be held
D. being held
答案：D
离子检验的常用方法有三种：
| 检验方法 | 沉淀法 | 显色法 | 气体法 |
| 含义 | 反应中有沉淀产生或溶解 | 反应中有颜色变化 | 反应中有气体产生 |
A．NH4+：气体法
B．I-：沉淀法
C．Fe3+：显色法
D．Ca2+：气体法