[lojban-beginners] Question around beginner's chapter 4

[Yann Le Du <yann.ledu@noos.fr>]

Hello,

I'd like some explanation on the existence of, and difference between, the 
following bridi :

.i le ci le gerku cu blabi

.i le ci lo gerku cu blabi

.i lo ci lo gerku cu blabi

.i lo ci le gerku cu blabi

Also, it is mentioned in "the complete lojban language", p. 132, section 
8, that on can omit "lo" e.g. "ci lo gerku" => "ci gerku". So am I right 
to conclude that "le ci gerku" is in fact the same as "le ci lo gerku" ?

--
mi'e .ian.xek.