阅读短文，回答下列各题： Mr．Black was young and able．The boss liked him．Last month he was sent toChina on business．Before hewent back from China，he decided to buy something for Tony，the sonof his boss．At first he didn’t know what to buy for theboy．Suddenly he remembered that the boy liked birdsvery much，so he went to the bird market．He wasglad to find that there were so many kinds of birds there．He bought four beautiful birds，then he toldthe boy about it on the telephone． As soon as Mr．Black returned to Londonby air，he went to Tony with the four birds．But on his way to theboss’s home，one of themflew out of the cage(笼子)and there were only three birdsleft in it．Then Mr．Blackboughta local(当地的)bird to take the place of the missing Chineseone． Tony of course was very happy when he saw the birds．Butsoon he found one of them was different from the other three．Heasked，“It’s a local bird，isn’tit，Mr．Black?” “Yes，it is．”Mr．Black answered，“It’s an interpreter(译员)．” Why did theboss send Mr．Black to China on business?