英文句子文法

I think sentence 1 is better because it can have a ask for future and this is more suitable for thia question.

The first one is correct.

The second one is wrong grammatically.
Grammatically, rabbit is singular, you should use 'wins' not win
However, if you write: 'Do you think the rabbit wins the race?' , it's not right logically. It's because if you ask somebody to think about it, so it's assumed the race hasn't taken place yet, so it's in the future. Therefore, use future tense (will win) rather than present tense.

If the race took place already and you want somebody to guess, then you may use past tense or present perfect tense.

Guess if the rabbit won / has won the race.

第一句是預測, 沒問題.

第二句用現在式(present tense)時, 可作常理解. 不過"the rabbit" 應 用"wins"對應( 因是單數).

另外, 如比賽已完畢, 只想問賽果, 可寫成:

"Do you think the rabbit has won the race?"

Both are correct.

“Do you think the rabbit will win the race?”

=> Race hasn't finished yet. You are asked the opinion about the probability that the rabbit will win.

“Do you think the rabbit win the race?”

=> Result of the race is known. You are asked whether the rabbit win the race.

兩句都可以
第一句無咁肯定
第二句較肯定