In fact, the answer on the first floor is not unreasonable. The year of Wu Geng should be 1990. Generally, rice paper will oxidize and yellow after more than 20 years (unless you treat it with ps), and this work has not been framed. If it is the original, it will be folded or sandwiched in other things. Look at the crease of this work, it should be a new work.
Judging from the style of his works, Mr. Zhang Hai often writes official script, with the words on the lower right, but it is steady.
Moreover, it is impossible for today's calligraphers to write works, going back 20 years.
Personal opinion, for reference only! !