题目内容：

Fifteen-year-old David had spent six months planning a hike to the bottom of the Grand Canyon (大峡谷)with his classmates. No one could have known it would end in tragedy.

When the group arrived at the starting point for the hike, they found out there was a problem with their permit. To solve it, the five boys and three leaders walked back up to the ranger station (护林站）一only to find out it was closed.

When the boys got moving, they'd already drunk most of their water. In the burning sun, temperatures reached a 115°F. Even the leaders were having trouble walking on. But the group finally made it down to the bottom of the Grand Canyon. Heat evil was occurring. "My son made it about 100 yards from the river and then dropped," says his father, Robin. Two boys of them raced to the river to get him water.

When the boys arrived, the last rafting （筏运) trip of the day was passing by. As luck would have it, among the waiting riders were a few doctors. They rushed to give David first aid before going for help. But it was too late. David passed away from the heat evil.

It's been 21 years since the boy's death, and hiking still holds a strong memory of David for his family. The summer before the tragedy, his father had a long time to devote to his family. David and his dad spent the summer hiking all over the High Uintas, where snow-topped peaks reflect tower over glacier(冰川) formed lakes.

The photo Robin took of Christmas Meadows there won the Reader's Digest "From Sea to Shining Sea" photo contest and appeared on the July 2017 magazine cover. To Robin, it isn't just a fascinating landscape--it's also a powerful reminder of his late son.

1.How many people does David's group consist of?.

A. 11    B. 10

C. 9 .    D. 8

2.What does the sentence "Even the leaders were having trouble walking on." in Paragraph 3 suggest?

A. The leaders were taller and older.

B. The leaders covered shorter distance.

C. The leaders were healthier and stronger.

D. The trouble the group faced was so great as to be beyond expectation.

3.Where did Robin take the photo which won the Reader's Digest "From Sea to Shining Sea" photo contest？

A. On the High Uintas.    B. Where David had been to.

C. In the Grand Canyon.    D. In the Christmas Meadows.

4.What does the passage intend to tell us mainly?

A. Take enough water with you when hiking.

B. Don't hike to the Grand Canyon in too hot weather.

C. Robin still misses his late son, David.

D. Doctors can't necessarily succeed in saving every patient.