Is "is" in this sentence necessary?

Question

I'm a Chinese student, and in my recent writing exercise, I wrote a sentence as follows:

Maybe he is not capable of conquering the sea now, for his flesh too weak, his strength so poor and his will not steady enough.

And my teacher marked that in the three separate sentences, "is" is necessary, and the correct sentence should be:

for his flesh is too weak, his strength is so poor and his will is not steady enough.

I'm now confused, I've seen sentences like the first one before, so is it correct to write like the first sentence?

Answer 1

The sentence is correct with the three extra 'is's, but also with only one of them. The first extra 'is' is necessary, but it's presence is then "assumed" after flesh and strength. "Maybe he is not capable of conquering the sea now; for: his flesh is too weak, his strength so poor and his will not steady enough."

I would also put a semi-colon after "now" to separate the initial statement from the explanatory list. (If there were only one or two reasons why he may not be capable, a comma would suffice.) In other words, a comma there has a different purpose than the one after "weak".