In 1990，Ed Viesturs started for the top of Mount Everest （29，029 feet） from a high camp at 27，000 feet．He planned to climb it without oxygen tank，something only a few climbers had managed to do．He'd failed twice，once getting with 300 feet of the top before turning back．

    He left his high camp at 1a．m．，using a headlamp to find his way in the dark．He'd already been on the mountain for two months，receiving endurance and strength training in preparation for the Everest climb．He'd also lived through terrible cold，strong winds，and separation from friends and family．

    "The common practice was to use oxygen when climbing，as it，in fact，lowers the altitude （海拔） of the mountain by several thousand feet，"says Viesturs．"If I couldn't climb Everest without oxygen tank，I wouldn't climb it．"

    "You have to be physically fit，"he says．"But the mental （精神的） part is big．It's so hard to keep going above 20，000 feet．"

    While making that final climb on Everest，he breathed 15times for every step．He would tell himself to first reach the rock 100 yards ahead．Then he'd find another rock，then another．Finally he stood on the top，with the whole world at his feet．"It was one of those dream﹣come﹣true moments，"Viesturs says．

    Today，Viesturs makes his living in part as a speaker，talking about his climb of Everest and of the world's 13other highest mountain，all without oxygen．He helps people find the strength to overcome their difficulties．

    Finally，in his words，"The art of mountaineering is knowing when to go，when to stay，and when to turn back．We should go step when working toward our dreams．There are no shortcuts to the top．"

（1）What does the article mainly talk about？　　

A．Viesturs'first successful climb of Mount Everest．

B．Viesturs'physical preparation for climbing Everest．

C．The difficulties that Viesturs has met in his life．

D．The lessons that Viesturs can share with others．

（2）What do we know about Ed Viesturs？　　

A．As soon as he reached Mount Everest，he set out for Everest climb．

B．He's been to the top of the world's 14highest mountain without oxygen．

C．Well prepared，he had no difficulty climbing the top of Mount Everest．

D．So far，he is the only one to have reached the top of Mount Everest without oxygen．

（3）The first "it" in Paragraph 3 refers to （指的是）　　．

A．being physical fit

B．climbing Everest

C．using oxygen when climbing

D．climbing without oxygen

（4）Which sentence should go in the empty box in the last paragraph？　　

A．I like being near the top of a mountain．

B．Life is like climbing a mountain．

C．You never climb the mountain twice．

D．Over every mountain there is a path．