5). Je
This is a preposition with an indefinite meaning i.e. it is used whenever there does not seem to be any other suitable preposition. In fact its normal usages are with dates and times. e.g.
je kioma horo? (At what time?); je la 6a de Aûgusto (on the 6th of August)
There are, however, a few other times when it is used e.g.
je via sano (your health - when toasting someone)
mi vetas je ^cevaloj (I bet on horses)
6). Special use as Prefixes
Prepositions cannot be isolated in Esperanto and so to translate something like 'to put on' we use a compound word (surmeti).
There are occasions, however, when the use of a preposition in forming a compound word alters the meaning slightly e.g.
sub : often conveys the meaning of something undesirable or underhand. e.g.
a^ceti (to buy) suba^ceti (to bribe); aûskulti (to listen to) subaûskulti (to eavesdrop)
el : often conveys the meaning of fully or thoroughly e.g.
uzi (to use) eluzi (to use up, wear out) ; ^cerpi (to extract) el^cerpi (to extract fully, exhaust); trinki (to drink) eltrinki (to drink up)
pri : makes a root somewhat more personal e.g.
^steli (to steal) pri^steli (to steal from, to loot); ser^ci (to search) priser^ci (to search someone)
7). ^Cu ne?
Most languages have the rather strange habit of asking a question by making a statement and then following by asking whether the opposite is true e.g.
You are going, aren't you? or You are not going, are you?. French uses 'n'est-ce pas?' or German 'nicht wahr?'
Esperanto uses ^cu? or ^cu ne? Thus
Vi ne iras, ^cu? (You are not going, are you?)
Vi iras, ^cu ne? (You're going, aren't you?)
8). Unu la alian
This is a useful phrase for one another e.g.
Ni amas unu la alian (We love one another) (one the other)
Similarly
Ili ne parolas unu al la alia (They do not talk to each other)
9). The latter, the former
When we refer backwards through the context to the persons mentioned we reach the latter first and have to move farther through the passage before arriving at the former. Remember that Esperanto uses ^ci to show proximity- so
Mi renkontis Tomason kaj Henrikon. Mi estis ^ce la sama lernejo kiel tiu, kaj la sama universitato kiel ^ci tiu.
I met Thomas and Henry. I was at the same school as the former (Thomas) and the same university as the latter (Henry)