Hi, this is something I've been wondering about for a while and am just now getting around to asking (mostly because this is the first time in months that I've actually been able to get on Lernu.net):

What is the main difference between -is/-as/-os and -inta/-anta/-onta? Are they interchangeable? Are there certain situations where one should be used instead of the other? Is there any significant difference in meaning between "Mi faras" and "Mi estas faranta"?

I've read descriptions of both suffixes, but I'm afraid I just don't understand the difference. To me, it just looks like -is/-as/-os would make more since to native speakers of some languages and that -inta/-anta/-onta would make sense to native speakers of others, because of it's required use of "est-."

The participles indicate aspect of action. Tense is only expressed by verbs (for example esti), but not by participles.

AleksandroRegho:What is the main difference between -is/-as/-os and -inta/-anta/-onta? Are they interchangeable? Are there certain situations where one should be used instead of the other? Is there any significant difference in meaning between "Mi faras" and "Mi estas faranta"?

In English, when we say "I drink coffee" we are referring to an habitual or customary action. When we say "I am drinking coffee" we are referring to an action that is taking place at the moment. In Esperanto, "Mi trinkas kafon" could be understood either way, depending on context. In general, the simple present is to be preferred when the meaning is clear. Don't say "Mi estas trinkanta kafon" when the simpler form is adequate.

However, there are times when the simple form is not adequate. For instance, if you say: "Mi trinkis kafon kiam li eniris" do you mean that you were already drinking coffee at the time he entered or do you mean that you had your coffee upon his arrival? "Mi estis trinkanta kafon kiam li eniris" makes it clear that you were already drinking coffee when he came in.

The main difference between the two forms is that "Mi estis trinkanta kafon" can only be understood one way and is therefore more precise at times when such precision is necessary.

I think (and I'm sure someone will correct me if I'm wrong) the -inta -anta -onta forms create adjectives more often than they translate English verbs. Naskonta virino = pregnant woman (woman who will be giving birth); dormanta hundo = sleeping dog, dorminta komunumo = a community that was asleep.

Mustelvulpo:

AleksandroRegho:What is the main difference between -is/-as/-os and -inta/-anta/-onta? Are they interchangeable? Are there certain situations where one should be used instead of the other? Is there any significant difference in meaning between "Mi faras" and "Mi estas faranta"?

In English, when we say "I drink coffee" we are referring to an habitual or customary action. When we say "I am drinking coffee" we are referring to an action that is taking place at the moment. In Esperanto, "Mi trinkas kafon" could be understood either way, depending on context. In general, the simple present is to be preferred when the meaning is clear. Don't say "Mi estas trinkanta kafon" when the simpler form is adequate.

However, there are times when the simple form is not adequate. For instance, if you say: "Mi trinkis kafon kiam li eniris" do you mean that you were already drinking coffee at the time he entered or do you mean that you had your coffee upon his arrival? "Mi estis trinkanta kafon kiam li eniris" makes it clear that you were already drinking coffee when he came in.

The main difference between the two forms is that "Mi estis trinkanta kafon" can only be understood one way and is therefore more precise at times when such precision is necessary.

In "I drink coffee" I use habitual aspect. I understand that "mi trinkas kafon" is vague. But how to explicitly express habitual aspect? Only with "ofte" or similar words?

In "I drink coffee" I use habitual aspect. I understand that "mi trinkas kafon" is vague. But how to explicitly express habitual aspect? Only with "ofte" or similar words?

For example:
Mi trinkadas kafon
Mi kutimas trinki kafon

If you are on your way to the counter to order for your friend then Ĉu vi trinkas kafon? obviously means Do you drink coffee.

If your friend has a cup of something (unidentified) before him then Ĉu vi trinkas kafon? obviously means Are you drinking coffee.

You will see the advice trotted out regularly that the complex verb forms are best avoided, but sometimes they are necessary for clarity.

Dankon ĉiuj!! It makes a lot more sense now!