How to build "..that.." sentences in Turkish

I am so lucky to meet hardworking Turkish Learners while trying to help; as you ask more I get the chance of helping you more. A hardworking Turkish Learner sent me a great question and I thought that all my readers should see my answer here.

Have you checked the most popular lesson of all times in this blog?
http://blog.learnturkisheasy.com/2012/07/oldugunu-that-is.html

Let me tell you briefly what that lesson is about.
It teaches you how to build sentences like
Onun güzel olduğunu biliyorum. I know that she is beautiful.

I explained how to make sentences that have "that, who, what, which" in the middle.
It was an introduction to make a way to use all the verbs easily with that kind of sentences.

Let's have a look at 3 sentences below now:
I saw that she went to the cinema yesterday
Onun bugün sinemaya gittiğini gördüm.

I heard that you have been ill / were ill
Hasta olduğunu duydum.

I saw that Ahmet wrote a long post
Ahmet'in uzun bir yazı yazdığını gördüm.

**!!! It seems like all these sentences have two verbs Gül! What's happening!

I know how they seem, I know how you feel about them, maybe you almost want to ignore them, but do you know that there are just three simple rules to follow? And then you will make and understand these sentences  as children play with toys. And good news: there is no exception. (A Turkish expression that I love) 

*now we take the verb gitmek for all pronouns in starting from I
gittiğim/gittiğin/gittiği/gittiğimiz/gittiğiniz/gittikleri-gittiği
it is like we take the conjugation for "we" in past tense and add genitive suffixes.

/-just to remind you vowel harmony; gördüğün, uyuduğun, yaptığın/
when we need connection letter we use "n" so it is usually same for "you" and "he/she"

for example:
look what he does / what you do
yaptığına bak

*it is same for past and present but in the future tense;
we take the future 3.person and add genitive again
gitmek - gidecek - gideceğim, gideceğin, gideceği, gideceğimiz, gideceğiniz, gidecekleri

I told him that I will go.
Ona gideceğimi söyledim.

I told him that she will go.
Ona gideceğini söyledim.

**in the present tense : rule is same with the past tense
I see that you are feeling good today
Bugün iyi hissettiğini görüyorum.

I can't see what she is doing.
Ne yaptığını göremiyorum.

**We have "ki" also but it is not so common to use.
When you use ki you build the sentence just as normal, in its real tense.

I told him that we will also join.
Ona dedim ki biz de katılacağız.
Bizim de katılacağımızı söyledim.

**or the sentences like having "what,who" inside;
I do not know who they are.
Bilmiyorum onlar kim.
Onların kim olduğunu bilmiyorum.

I can't see what she is doing.
Ne yapıyor göremiyorum.

If you use these alternatives everyone will sure understand and they are not wrong,
but the first forms with those suffixes are the common ones.

Also see http://blog.learnturkisheasy.com/2012/07/what-is-your-favorite-food.htm which uses the same rule and helps you to tell what your favorites.

Hope it is clear, for any questions you know what to do -_o