两性表面活性剂的分子内同时含两个亲水性基团，在酸性溶液中呈阳离子活性，在碱性溶液中呈阴（）。
参考答案：离子活性
按要求完成下列句子。
1. She's never been to Tokyo. (改为反意疑问句)
She's never been to Tokyo, ______ ______?
2. It'll be sunny tomorrow. (改为反意疑问句)
It'll be sunny tomorrow, ______ ______?
3. The boys were having a math class at this time yesterday. (改为反意疑问句)
The boys were having a math class at this time yesterday, ______ ______?
4. Go across the bridge, and you'll see the hospital. (改为同义句)
______ the______, and you'll see the hospital.
5. This book cost Peter 5 yuan. (改为同义句)
Peter ______ 5 yuan ______ this book.
如果长时间不使用电动车，每隔（）应充一次电，亏电存放会严重影响电池寿命。
A.10天
B.40天
C.30天
D.50天
