Because of the rule called palatalization. When batchim/ending consonant ㅌ followed by 이, the sound becomes ㅊ sound.
Ok, not sure if this would help but I'll leave a note for those who are trying to memorise these verbs. 생각 means a thought or an idea in Korean, and 합니다 means doing. So put together, it literally means doing the thought, or thinking. This applies to many verbs, but what makes it so difficult for non koreans is that there are so many variations. For example, just off the top of my head I can think of 생각을 합니다, 생각이 납니다, 생각이 떠오릅니다, 생각이 듭니다, although the latter three actually mean a thought/an idea occurred to me. But this illustrates the wide range of expressions that can be built around the term 생각. What adds to the difficulty is you wouldn't use 합니다 in a normal conversation. For instance, if I were talking to an older person, I would likely say 같이 생각하고 있어요 as opposed to the super formal expression of 같이 생각합니다. If you were talking to your boss at your workplace, you might say something along the lines of (저희가) 같이 생각하고 있습니다 but again, if I am to be critical, 같이 생각하다 just doesnt sound very natural/common. 같이 고민하다 has a different literal meaning but more likely to be used in real life if the subject matter is an issue of some sort. Sorry I have rambled on a bit but I think it's important to be aware that whilst many expressions you study using this app would help improve one's grammar/vocabulary, they do seem a bit awkward in the sense that they focus on literal translation rather than based on what Koreans actually speak/write.
if ㅌ is the third letter in a syllable and is followed by a vowel sound
Specifically the rule is: final ㅌ + 이 → 치.
- Google "Palatalization"
I wrote: Together, the men are thinking and got it wrong.
In any case, shouldn't we be starting with a simple verb structures? Like I am reading a book, she is reading a book, they are reading a book, who is reading a book and moving on from there. Is anyone else seeing this?
In French, it goes through simple phrases plus the colours, food and other items before it gets to verbs and adjectives.
When learning through activities like this particular one is it more about learning the grammar and translating with the pronunciation as more of an afterthought or is the pronunciation just as important at this stage? I ask cause I find it hard to understand the machine pronunciations at times.