Successful landing on the Moon by the human being,which has magnificent significance,is the great milestone in the history of Aeronautics ..
你说的也可以.至于为什么不是successfully landing是因为landing在这里是名词,而successfully是副词,是用来形容动作,所以要用successful,not successfully.
不是,在这里,land后面加了ing,而且是作主语,所以只能算作名词,不能用successfully.
如果说 This aircraft is landing,这时可用successfully来修饰.
英文里,有很多动词+ing 变成了名词,也有加其它后缀成为名词,例如 prosper(使繁荣,v) + ity = prosperity(繁荣,n).所以你要根据句子来判定这到底是动词还是名词.