Only the first one, 'That is worth reading' is correct. 'Worth' is an adjective, and it is followed by the gerund (ing form).
Don't believe anyone who tells you that you can say 'worth to' with the infinitive - this is wrong.
June 27, 2016
3
6
4
That is worth reading
June 27, 2016
1
4
4
That is worth reading
June 27, 2016
1
4
0
You should use "reading"
June 28, 2016
0
0
0
It/ That is worthy to read.
June 27, 2016
0
0
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