Output formats of chm2pdf

[Tim]

On Ubuntu 10.10, I am trying to use chm2pdf 0.9.1 to convert a chm
file into a pdf file.

The hint of the command says that "Either '--book' or '--webpage' or
'--continuous' MUST be given!"

1.I first tried '--book' option, but

$ chm2pdf --book 1.chm
ERR002: Error: no pages generated! (did you remember to use
webpage mode?
Something wrong happened when launching htmldoc.
exit value: 256
Check if output exists or if it is good.
Done.

I also tried this option on other chm files, and all failed. I
wonder why and how I can get the nice book format output? My htmldoc
version is 1.8.27.

2. I then tried the other two options --webpage or --continuous.
The output of both are both broken down into pages, except that with --
continuous there are fewer pages, and the files look no other
differences to me. So I wonder what do they differ actually?

Thanks and regards!