放弃现金折扣的成本受折扣百分比、折扣期和信用期的影响。下列各项中，使放弃现金折扣成本
题型：多项选择题
问题：
放弃现金折扣的成本受折扣百分比、折扣期和信用期的影响。下列各项中，使放弃现金折扣成本降低的情况有（）。
A.信用期、折扣期不变，折扣百分比提高
B.折扣期、折扣百分比不变，信用期延长
C.折扣百分比不变，信用期和折扣期等量延长
D.折扣百分比、信用期不变，折扣期缩短
题型：多项选择题
Summer vacations should be relaxed for students. However, many of them use the opportunity to take part in summer project.
Xu Dan,a 15-year-old girl , loves vacations because it means she can spend more time volunteering. She believes that volunteering has cts instead. changed her life and made her a better person.
Two years ago, Xu was a shy girl. One day, she saw a group of volunteers picking up trash in the street. Since she had no plans for the summer vacation and wanted to make some friends, she decided to join them.
“I used to think volunteering was nothing more than picking up trash. Now I know that the aim of volunteer work is helping others and gaining self-esteem(自尊),”Xu says. Her volunteering schedule is full: teaching migration workers’(外来务工人员) children English from Mondays to Fridays, picking up trash on Saturdays, and visiting old people on Sundays.
For Xu, visiting old people is the most meanful activity. “I help them clean their homes and cut their hair. I talk to them and listen to their life stories. These are just small things, but every time I help others I feel more confident about myself,” Xu says.
According to Xu, the positive energy(正能量) from volunteering influences the way she deals with people and sees the world. “I can see things from other people’s point of view and look at things more positively. I think I’m going to hold on to it all my life.” she says.
小题1:Xu Dan loves to spend more time_______ during vacations.
A．studying
B．reading
C．traveling
D．volunteering小题2:When did Xu Dan start volunteering?
A．When she was 14 years old.
B．When she was 15 years old.
C．Two years ago
D．Three years ago.小题3:Why did Xu Dan decide to join volunteers at first?
A. She didn’t have any plans for the summer vacation
B. She wanted to make some friends
C. She wanted to get more experiences.
D. Both A and B.
小题4:What does Xu Dan do on Sundays according to her volunteering schedule?
A．She visits sick people.
B．She visits old people
C．She picks up trash .
D．She teaches migration workers’ children English .小题5:Which of the following is NOT ture according to the passage?
A．Xu Dan believes that volunteering has changed her life.
B．Xu Dan used to think volunteering was just picking up trash.
C．Xu Dan thinks teaching English is the most meanful activity.
D．Xu Dan will continue volunteering.