Note.—The Compound Tenses should not be used if the Simple Tenses suffice to show the meaning clearly. Thus, I have seen him is more neatly expressed by mi jam vidis lin than by mi estas vidinta lin. Li jam foriris might stand for either he had gone or he has gone, according to circumstances, and the context would clearly show which was meant. Li parolas is generally quite right for he is speaking. Li estas parolanta should be used only when it is particularly intended to show that he is actually engaged in the act of speaking.
The Adverb.
In Esperanto, Adverbs are denoted by the ending -e, and may be placed in any position, either before or after the verb. Thus: bela, beautiful—bele, beautifully; vera, true—vere, truly. Li parolas saĝe, he speaks wisely. Li rapide kuras, he runs quickly.
Adverbial Numbers.
Adverbial Numbers are formed by adding -e to the Cardinals. Thus: unue (1e), firstly; trie (3e), thirdly; sepe (7e), etc.
The Preposition.
In English, one preposition often has many different meanings. In Esperanto, on the contrary, every preposition, with the exception of the word je, has one precise and fixed meaning.
The preposition je is the only one in Esperanto without a definite meaning. It sometimes happens that one wishes to use a preposition of some sort or other, but is uncertain just which preposition will precisely express the idea. In such cases je is used. Thus: He laughed at me, li ridis je mi; full of water, plena je akvo; six metres long, longa je ses metroj; fear of him, timo je li, etc.
Je should not be abused. Its too frequent use is a mark of the beginner in the language.