Since "I think it's raining today" is a poem, "thinking" and "raining" should rhyme. Judging from the pronunciation of modern Chinese, these two words can't match, but we can still feel that their pronunciation is a little close. However, the pronunciation of "contraction" is far from these two words, so it is impossible for "thinking" to pronounce "contraction".
Look at the pronunciation of these words in ancient Chinese:
S: Xi Chisis: Cut the child: Stop and cut it: If you cut it.
F: No, no, nothing.
Shrinkage: six scissors: strong bamboo scissors: jade scissors: fish wants to cut: cut Shu scissors: city jade scissors.
It is not difficult to see that in ancient Chinese:
The vowels of "Si, Zi, Zhi and Er" are the same, the vowels of "Fei, Fei and Wei" are the same, and the vowels of "contraction, six, bamboo, jade, desire and Shu" are the same. No matter what the vowels of these three groups of words are, it is certain that the vowels of these three groups of words are different. The remaining question is: who is closer to whom?
The vowel of "contraction" is today's U or ü, the vowel of "Si" is basically today's I, and the pronunciation of "Fei" is today's ei. Obviously, the vowels of "contraction" are far from the other two groups, while the vowels of "thinking" and "non" are relatively close.