When two third-tone syllables are read in sequence, the first syllable turns into the second tone, i.e., the 3+3 sequence becomes a 2+3 one.However ,when put in written form, the original tone is kept.

Hello I want to make a supplement. :) The tone transition of "一“ yī 1.When “一” is used alone or at the end, it is pronounced as the first tone, yī. 唯一 wéi yī (sole) 2. When “一” is used before the fourth tone, it is pronounced as the second tone, yí. 一样yí yàng (same) 3. When “一” is used before the first tone, second tone and third tone, it is pronounced as the fourth one, yì. 一年 yì nián (one year) 一起 yì qǐ (together) Also when we say 爸爸bà ba (father）爷爷yé ye（grandfather) etc. The second word is neutral tone.

我来举例子😄 你好： ✏️nǐ hǎo — 🗣ní hǎo 广场： ✏️guǎng chǎng — 🗣guáng chǎng 水果： ✏️shuǐ guǒ — 🗣shuí guo 美好 ✏️měi hǎo — 🗣méi hǎo tip:The above are just examples. In fact, you don’t have to think about what tones to change before you speak. Sometimes you can just say it, maybe the other party will tell you the correct pronunciation. :)

Hello here are some examples. The original tones are the third tone for both characters, but in spoken Chinese, we will change the tone of the first character into the second tone. 3-3⥤2-3 老虎lǎo hǔ --- láo hǔ（tiger） 小姐xiǎo jiě --- xiáo jiě (miss) 雨伞yǔ sǎn --- yú sǎn (umbrella) But if you need to write down the pinyin for these words, the written version keeps same (the third tone)