US First Lady Helps Children Track Santa

 　　U.S. first lady Michelle Obama spent some time Saturday answering calls from children across the country who were hoping to find out where Santa Claus was on Christmas Eve.

　　Just as she did last year, the first lady took calls from the NORAD Tracks Santa program, run by the North American Aerospace¹ Defense² Command.

　　The military base has been telling anxious children about Santa's whereabouts every year since 1955, when a local newspaper advertisement giving a telephone number to speak to Santa mistakenly directed children to a military defense operations center. Officers on duty answered the children's questions and NORAD has been doing the same ever since.

　　Last year, more than 1,200 volunteers took shifts³ at NORAD's facility in the western state of Colorado to field more than 80,000 calls and countless⁴ emails from children asking where Santa was and when he might be coming to their homes to deliver presents.

1 aerospace   

adj.航空的，宇宙航行的

参考例句：

• The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
• Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。

2 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

3 shifts   

n.转换( shift的名词复数 )；切换键；（汽车等的）变速；更换v.改变( shift的第三人称单数 )；去掉；摆脱掉；换挡

参考例句：

• The action of the novel shifts from Paris to London. 小说情节从巴黎移到了伦敦。
• I work split shifts in a busy restaurant. 我在一家繁忙的餐馆上间隔班。

4 countless   

adj.无数的，多得不计其数的

参考例句：

• In the war countless innocent people lost their lives.在这场战争中无数无辜的人丧失了性命。
• I've told you countless times.我已经告诉你无数遍了。