We are pleased to know that you have planned to come to the Autumn Guangzhou Fair.We wish to discuss with you some other important things if you could come（）your earliest convenience.
A. by
B. on
C. in
D. at
奈斯勒试剂法是鉴定（）离子的。
Ag+
B. NH4+
C. Na+
D. Cu2+
与螺旋CT时间分辨力相关的是（）。
A. 采集速度
B. 扫描层厚
C. 扫描部位
D. 重建时间
E. 曝光条件
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