This lesson is something of a mixed bag. In it, we cover four topics which are fairly important in Lojban, each of which kind of fits somewhere else — but would take us far afield in each of the other lessons. Aspects are a special kind of tense; vocatives are a special kind of attitudinal; loan words are a way of introducing new words into Lojban, comparable to lujvo; and equalities involve a special kind of selbri.
We've seen that we can locate our bridi in space and time, by using tenses. But this is something of a simplification. We can't just say that events are before, simultaneous with, or after other events, because events have beginnings, middles and ends. They are not simply points that can be lined up on a timeline.
And we tend to be very interested in the beginnings and ends of events. There is quite a difference between these three sentences:
Is he about to do his homework?
Is he still doing his homework?
Has he done his homework yet?
The term in linguistics for situating the beginnings and ends of events is aspect. The term Lojban uses is event contours: events are perceived as shapes, which have beginnings and ends. (This is why Lojban can use its aspects in space as well as time, although we won't be going into that here.) In many languages, aspect is as important as tense, or even more important. In Russian, to use the best-known example, you cannot use a verb at all without choosing between a stem indicating that something is (or was, or will be) still going on (imperfective), and a stem indicating that something is (or was, or will be) completed (perfective).
English isn't like that: you can quite often leave off any indication of aspect in your verbs. Yet English has ways of expressing aspect anyway. When we say "I have spoken to the doctor", we are also indicating that we have now finished doing so — we are after the end of the event. When we say "I am speaking to the doctor", on the other hand, we are also indicating that we are in middle of the event: the event is continuing, and is not yet over.
Note: Aspect is quite independent of tense: you can say that something will be over some time in the future ("I will have spoken to the doctor [by then]"), or that something was continuing in the past ("I was speaking to the doctor"), without giving any indication of what is happening in the here-and-now.
Lojban uses cmavo belonging to selma'o ZAhO to express event contours. You use them just like tense words; if you use both, the tense word goes first. The three-way distinction we made — before the beginning, in the middle, after the end — is made with three distinct words: pu'o, ca'o, ba'o. This is, of course, no coincidence: before (pu) an event begins, you use pu'o; after (ba) an event ends, you use ba'o. So you can come up with sentences like these:
mi ba'o tavla le mikce
I have spoken to the doctor (or had spoken, or will have spoken)
mi ca'o tavla le mikce
I am speaking to the doctor (or was speaking, or will be speaking)
mi pu'o tavla le mikce
I am about to speak to the doctor (or was about to speak, or will be about to speak)
mi pu pu'o tavla le mikce
I was about to speak to the doctor
mi ba ba'o tavla le mikce
I will have spoken to the doctor
mi pu ba'o tavla le mikce
I had spoken to the doctor
mi pu ca'o tavla le mikce
I was speaking to the doctor
insane, crazy person (fenki 'crazy' + prenu 'person')
x1 tries/attempts/makes an effort to do/attain x2 (event/state/property) by actions/method x3
Translate into Lojban.