It is so heavy a bag that the old man can't lift it up.
The bag is so heavy that the old man can't lift it up.
So heavy is the bag that the old man can't lift it up.
The bag is too heavy for the old man to lift it up.
The old man can't lift the bag up,for it's too heavy.
如有不明白的再问哟!请记得采纳,