Turkish Language - the Potential Mood - Positive

The Potential Mood (tense) indicates: ability - "to be able, can.." or disposition - "may, might.."

The Potential Mood uses the addition of bilmek - to know - to form its sense of meaning, therefore it always takes the form with a dotted i - and is not subject to vowel harmony, as bilmek is a word in its own right.
This is similar to the Scottish use of - "ken" - "can, be able to. . " - where they can say - "Do you ken the swimming?" - "Do you know how to swim?"

Positive Potential Mood

Verb Stems ending in a Consonant
The suffix-ebil- or -abil- is affixed to the positive verb stems which end in a consonant,
gelmek - to come forms a new verb and becomes gelebilmek - to be able to come
yazmak - to write forms a new verb and becomes yazabilmek - to be able to write
yazılmak - to be written [Passive Mood] forms a new verb and becomes yazılabilmek - to be able to be written
gülmek - to laugh forms a new verb and becomes gülebilmek - to be able to laugh
güldürmek - to make s.o. laugh [Causative Verb] forms a new verb and becomes güldürebilmek - to be able to make s.o. laugh

Verb Stems ending in a Vowel
Verb Stems ending in a vowel add -yebil- or -yabil- - (buffer letter -y-)
yürümek - to walk forms a new verb and becomes yürüyebilmek - to be able to walk
taşımak - to carry forms a new verb and becomes taşıyabilmek - to be able to carry

In short
The various tenses can be formed as normal after dropping -mek or -mak - which are replaced by -e- or -a- to which the verb bilmek - to know - is affixed - thus forming -ebil- or -abil- as the Potential Mood Suffix. In essence what is really being formed is a new verb altogether, which is different from English which uses the auiliary verb - "to be able.."

Potential Mood Examples

Potential Mood -Present Continuous Tense:
gelebiliyorum - I can come, I am able to come, I may come, I might come

Potential Mood - Present Simple Tense:
gelebilirim - I can come, I am able to come, I may come, I might come

Potential Mood - Future Tense:
gidebileceksiniz - you will be able to go - etc..

Potential Mood - Past Tense:
başlayabildik - we could have started - etc..

Present Continuous

görmek - to see - becomes in the Potential Form - görebilmek - to be able to see
görebiliyorum - I can see, I am able to see, I may see, I might see.. - etc.
görebiliyorsun - you can see, you are able to see.. - etc
görebiliyor - he can see, he is able to see.. - etc.
görebiliyoruz - we can see, we are able to see.. - etc.
görebiliyorsunuz - you can see, you are am able to see.. - etc.
görebiliyorlar - they can see, they are able to see.. - etc.

Present Interrogative

The Interrogative is formed in a similar manner as the Basic Verb by using the correct question tag according to the number of the personal pronoun:
gelebiliyor muyum? - Can I come?.. etc.
gelebiliyor musunuz? - Can you come?.. etc

Future Tense Potential

kalmak - to stay, to remain - becomes in the Future Potential Form - kalabilmek - to be able to stay, remain
kalabileceğim - I will be able to stay
kalabileceksin - you will be able to stay
kalabilecek - he will be able to stay
kalabileceğiz - we will be able to stay
kalabileceksiniz - you will be able to stay
kalabilecekler - they will be able to stay

Future Interrogative

gidebilecek misiniz? - will you be able to go?

Past Definite Tense

beklemek - to wait, to expect - becomes in the Past Definite Potential Form - bekleyebilmek - to be able to wait, expect
bekleyebildim - I could have waited
bekleyebildin - you could have waited
bekleyebildi - he could have waited
bekleyebildik - we could have waited
bekleyebildiniz - you could have waited
bekleyebildiler - they could have waited

Past Indefinite Tense

düşünmek - to think - becomes in the Past Indefinite Potential Form - düşünebilmek - to be able to think
düşünebilmişim - it seems I was able to think
düşünebilmişsin - it seems you were able to think
düşünebilmiş - it seems he was able to think
düşünebilmişiz - it seems we wers able to think
düşünebilmişsiniz - it seems you were able to think
düşünebilmişler - it seems they were able to think

Past Interrogative

bekleyebildi mi? - could he have waited?

Past Continuous

yapmak - to do, to make - becomes in the Imperfect Past Potential Form - yapabilmek - to be able to do
yapabiliyordum - I was able to do
yapabiliyordun - you were able to do
yapabiliyordu - he was able to do
yapabiliyorduk - we were able to do
yapabiliyordunuz - you were able to do
yapabiliyorlardı - they were able to do

Imperfect Interrogative

durabiliyorlardı mı? - were they able to stop, halt ?
We can see clearly in this example where the verb - bilmek - to know - keeps its dotted i - as it is not subject to vowel harmony rules.