One afternoon Mrs. Green's husband wanted to catch the 3：30 flight to London to have an important meeting．She was very surprised when he telephoned her at 5 o’clock and said that he was still at the airport．

‘'What happened to you?” asked Mrs. Green．

“Well,” said Mr. Green，”Everything was going fine．I got my ticket，checked my luggage and waited in line at the gate．I walked across the runway to the airplane and I saw my friend Jack Scott, who was an airplane engineer．I shouted to him and a policeman caught me?”

      “Why did he catch you?’’

“I don't know．” said Mr. Green．”As soon as he heard my shout, he ran towards me and caught me?”

“What did you shout to your friend?”

“All I said was ‘Hi．Jack’．You know that's the usual way we say hello to our friends?”

    “But you don't know the sentence ‘Hi，Jack’ also means to take control of a plane by force（武力）．”

1．How was Mr. Green going to London?

2．Why was Mrs. Green surprised?

3．Who did Mr. Green meet when he walked across the runway to the airplane?

4．‘Hi．Jack’ is often used to say hello to somebody, but it also has another meaning．What is it?