题目内容：

    Paying it forward is a concept that involves doing something good for someone in response to a good deed done on your behalf or a gift you received. When you pay it forward, however，you don't repay the person who did something nice for you. Instead, you do something nice for someone else.

Recently, an inspiring note found inside a random book has inspired thousands of people to pay it forward.

Ashley Jost was shopping at Target when a book caught hex eye. The 27-year-old bought the book Girl Stop Apologizing and began reading it when she got home. After a few minutes her dog started barking so she put the book aside. When she got back, she noticed something on the ground. "A five-dollar note fell out, " Jost said.

She looked through the book, and in one of the last pages, there was a note that read, “To the person who buys this book: I am having a tough day. I thought maybe I could brighten someone else’s with this little surprise. Go and buy a coffee, a hamburger or a face mask. Practice some self care today. Remember that you are loved, you are amazing, and you are strong -Lisa”

Jost decided to post a photo of the note and the money on Twitter and it went like a virus. People are promising their own random acts of kindness.

“In that moment，I didn’t necessarily need the pick-me-up，but I feel obligated(有义务的)to share it， and I’m hearing back from people who did,” Jost said. “The ripple effect is pretty unbelievable.

After seeing her Twitter post, Lisa mailed Jost a card. "She said it made her cry in a good way,” Jost said. But Lisa still didn’t give away who she was. She left no return address. Lisa wrote it had been a difficult time in her life and she just wanted "to create something positive-she never really expected this to happen the way it has.”

1.What is the first paragraph mainly about?

A.The origin of"paying it forward". B.The effects of"paying it forward

C.The benefits of"paying it forward" D.The definition of"paying it forward".

2.Why did Lisa put a five-dollar note in a book?

A.To go through the hardest time in her life.

B.To cheer up the person who buys the book

C.To repay the person who did something nice

D.To set off a round of paying it forward

3.What does the underlined word "ripple" in Paragraph 6 mean?

A.Edge B.Chain

C.Mass D.Side

4.Lisa posted a card to Jost to ___________.

A.make friends with Jost B.tell Jost about her story

C.express appreciation to Jost D.let Jost know what made her cry