Some Changes with Present Continuous Tense

Some verbs changes by present continuous suffix -yor. Some examples:

a changes to ı
anlamak: anlıyor
kanamak: kanıyor
a changes to u
zorlamak: zorluyor
boyamak: boyuyor
e changes to i
dinlemek: dinliyor
demek: diyor
e changes to ü
özlemek: özlüyor

If you realized, the common point of these verbs are that the last letters of their roots are a and e. Now let's try to understand when and how it happens.

The root of anlamak is anla. -mak/mek is the infinitive suffix (mastar eki). The last vowel of anla is a. When we use it with present continuous suffix -yor, it changes to "ı".

Indeed, the present continuous suffix has a hidden letter inside. It is -(i)yor and it can be changed due to the last vowel of the verb root.

In out topic, all the roots finish with vowels "a" and "e". As a result, they cannot be together with another vowel in theory. Normally, when there are two vowels together for adding suffixes, we put buffers between these two vowels. But here, -yor's first vowel is hidden. And we have another solution: to make the last vowel similar to the closed vowels (ı/i/u/ü)

Step by Step

Step by step with another example "dinlemek" and "anlamak":
1. Find the root verb
Drop the -mek or -mak suffix in order to find the root verb.
dinlemek -> dinle
anlamak -> anla
2. Find the last letter
If the last letter of the root is the vowel "a" or "e", then we need this rule:
dinle
anla
3. Decide the type of this vowel. Is it hard of soft?
If the vowel is a soft vowel (e), we will change it as "i" or "ü". If hard (a), then as "ı" or "u"
dinli or dinlü
anlı or anlu
4. Now in order to decide this, we need to look at the previous vowel. If it is flat (a,e,ı,i), then we put "ı" or "i" (depends on major vowel harmony, see step 3). If round (o,ö,u,ü), then "u" or "ü".
dinli or dinlü; previous vowel: "i", it is flat, so we choose flat and soft: "i" -> dinli
anla or anlu; previous vowel: "a", it is flat, so we choose flat and hard: "ı" -> anlı
5. Put the suffix -yor:
dinliyor
anlıyor

Now try this with zorlamak:
1. zorla
2. zorla
3. "a" is a hard vowel (a,ı,o,u) so we have two options
zorlı or zorlu
4. Previous vowel is "o". It is a round vowel (o,ö,u,ü). So we choose the round one: "u": zorlu
5. zorluyor

Make more exercises with the other example verbs above.