—______is the Changjiang river in China, do you know?

—Yes, it’s about 6,380 kilometers long.

A. How many B. How wide C. How long D. How much

Electronic books have changed the way many people read for   15 . Now online textbooks are changing the way some students learn and some teachers teach.
More than   16  students go to the public schools in Fairfax County, Virginia, outside Washington. Last year, the school system used digital books in fifteen schools. This school year, middle schools and high schools changed   17  printed to electronic textbooks in their social studies classes.
“I mean, it’s just   18  a regular textbook, except it’s got it all online.” says Luke Rosa, a history teacher at Falls Church High School.
Peter Noonan, an assistant superintendent(主管) of schools says, “The world’s changing   19 . And the online textbooks can change right along with the events that   20 .”
“Digital books also cost   21  than printed textbooks,” he says, “Usually it’s between fifty and seventy dollars   22  a textbook for each student, which adds up to about eight million dollars for all of our students in Fairfax County. In fact, we have bought all of the online textbooks for our students for just under six million dollars.”
Social studies teacher Michael Bambara says the e-book he uses in his government class is better than a(an)   23  textbook. It has materials for students   24  different levels of reading skills…

A little boy invited his mother to attend his school’s first teacher-parent meeting. To the little boy’s disappointment,she said she would go. This   16   be the first time that his classmates and teacher   17   his mother and he felt ashamed of her   18  . Although she was a beautiful woman, there was a scar(疤痕)that   19  nearly the right side of her face. The boy never wanted to   20  why or how she got the scar.
At the meeting, the people were impressed by the kindness and natural beauty of his mother in spite of the scar, but the little boy was still  21 and hid himself from everyone,  22   a conversation between his mother and the teacher.
The teacher asked   23 ,“How did you get the scar on your face?”
The mother answered,“When my son was a baby, he was in a room that caught fire. Everyone was   24  afraid to go in because the fire was   25   ，so I went in. As I was running toward his bed, I saw a piece of wood coming down and I placed myself over him trying to protect him. I was knocked senseless but   26  , a fireman came in and saved both of us.” She touched（摸著） the   27  side of her face. “This scar will be  28 ,but to this day, I have never regretted what I did.”
At this point, the little boy came out running toward his mother with tears in his eyes. He held her mother in his arms and   29   a great sense of the sacrifice(犧牲)that his mother had made for him. He held her hand tightly for the   30  of the day.