Answer the following questions. Your answer should be clear and short.Exemplify the various sources of homonyms.
（1）CHANGE IN SOUND AND SPELLING. SOME HOMONYMS ARE NATIVE BY ORIGIN, DERIVED FROM DIFFERENT EARLIER FORMS IN OLD ENGLISH. THE CHANGE IN SOUND AND SPELLING GRADUALLY MADE THEM IDENTICAL IN MODERN ENGLISH, E. G. LONG ADJ. NOT SHORT, FROM LANG(OE); LONG V. TO WANT VERY MUCH, FROM LANGIAN(OE).
（2）BORROWING. MANY WORDS OF FOREIGN ORIGIN COINCIDE IN SOUND AND/OR SPELLING WITH THOSE OF NATIVE ORIGIN OR WITH THOSE OF OTHER FOREIGN ORIGIN, E. G. BALL N. A ROUND OBJECT TO PLAY WITH, FROM BEALLU (OE); BALL N. A DANCING PARTY, BORROWED FROM BALLER(OF).
（3）SHORTENING. MANY SHORTENED FORMS OF WORDS HAPPEN TO BE IDENTICAL WITH OTHER WORDS IN SPELLING OR SOUND, E. G. AD N. SHORTENED FROM ADVERTISEMENT; ADD V. TO CAUSE AN INCREASE. 
