用离子色谱法对水中阴离子测定时，采集的水样应尽快分析，否则应在（）度保存，一般不加保存剂。
A.0
B.2
C.4
参考答案：C
根据句意或首字母填词。
1. —What do you usually do on w______?
—I often watch TV.
2. —How often does she shop?
—O______ or t______ a week.
3. Grandpa is pretty healthy because he e_______ every day.
4. Animal World is my favorite TV p_______
5. The weather here is so cold, I can h_______ stand it.
术后疼痛影响消化系统，表现为（）
A.恶心
B.呕吐
C.括约肌张力增加
D.胃穿孔
E.胃肠平滑肌痉挛
