Third tone sandhi: when (if ever) does 3 3 become 3 0 instead of 2 3?

Question

All of the books and materials I've seen talk about the tone sandhi that changes two third tones to a second and a third, as in "你好."

I had a question about the word:

寶寶

Some materials I've seen list this as "bao3 bao3". Based on the sandhi, I'd assume that this would be pronounced as "bao2 bao3." However, some materials have the word's pronunciation as "bao3 bao0" instead.

姐姐 is the only other word I remember seeing with this characteristic.

Is this a separate sandhi that says that a reduplicated character is always normal tone, neutral tone, that overrides the "3 3" sandhi? Is it a weird exception I just have to memorize? Or is there something else I'm missing?

Answer 1

"bao3 bao0" is actually not a third tone sandhi here.

It is because the tone of second bao3 got neutralized.

Usually a second character of a two-character word would get neutralized, I would say it is a accent thing that depends on people from different places of China.

Answer 2

I remember having the same question a few years ago.

I heard people saying 姐姐 as "jie3 jie" and 等等 as "deng2 deng".

My teacher told me that only family members got a 3-0 combination, while the other cases (like verbs) it would be always 2-0.

The other family member I remember is 奶奶 "nai3 nai".

Answer 3

30 姐姐，奶奶，好好学习，姥姥 and many other AA words.

But 23 等等再走，款款都好看，走走停停，朵朵都好看，跑跑步 because
等等 is short for 等一等 走走 is short for 走一走 跑跑 is short for 跑一跑 款款 is short for 每一款 朵朵 is short for 每一朵

when a word AA is short for A一A or 每一A 。it takes 23