阅读理解,怎么填,When you begin a letter in English,you always put "

阅读理解,怎么填,
When you begin a letter in English,you always put "Dear" before the name of the person you are writing to.When you write an offical letter to someone whose name yo do not know,you__1__"Dear Sir or Madam".
1空里填什么,是begin with 还是 write
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