tişört alacağına pantalon al --- buy a trouser instead of tshirt

and there are two more suffıxes have the same meanıng ( mak yerde . acağı yerine )

e.g

tişört almak yerde pantalon al

tişört alacağın yerine pantalon al

so the last two sentences also correct or not

The last form is mostly used for past & present tense.

Tişört alacağı yerde pantalon almış. ---> Instead of  buying t-shirt,he/she bought a trouser.

Seni anlamıyorum. Tişört alacağın yerde pantalon alıyorsun !

I don´t get you, you are buying trouser instead of buying a t-shirt ! 

* Note that this kind of comparasion contains feeling of being displeased with the person´s choice of buying more than a mere comparasion. In other words, "you are supposed to do this but you are doing something else instead"

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