这根本就不是一个sentence!应为singing不是谓语动词，而是一个非谓语动词。因此，把singing改成谓语动词，这句话就有谓语了。Miss Tian is singing a new song。 Miss Tian was singing a new song 。miss Tian sang a new song.Miss Tian has sung a new song.Miss Tian has been singing a new song.以此类推。具体改成什么，还得看上下文（context）...
