I'm teaching myself bopomofo/zhuyin keyboard while I'm in Taiwan. My Chinese level is raw beginner too.
I just came across the word for tofu:
We can see that the second syllable is tone 0 a.k.a. tone 5
But if I try to enter it using Microsoft Chinese Traditional New Phonetic IME this way the computer beeps and will not accept the final syllable.
When I look up just the last syllable on its own, it's actually tone 3:
If I type the whole word as
ㄉㄡˋㄈㄨˇ in the IME then indeed it does work.
So what's the explanation for this? Is it due to tone sandhi? Or is it a quirk of the IME? Or is it related to some other property of two syllable words and tone 0/5? Is there a name for this and where can I read more about it?
The English Wiktionary and Google Translate both list
豆腐 as having tone 4 + no tone. But I can't be sure whether they are listing pre- or post- tone sandhi rules.
But Baidu dictionary and the book "Chinese for Everyday Scenarios" I've found here in Taiwan lists
豆腐 as having tone 4 + tone 3.