Student or Learner
1.why did thief leave his bike there?
2.Why the thief would leave his bike?
I understand from above points is that both are in Past tense but I do not understand the usage of 'would' , can someone tell me about usage would?
Neither is correct.
1. "Why did the thief leave his bike there?"
2. "Why would the thief leave his bike?"
Note that all sentences begin with a capital letter.
The second is conditional. It's not past tense.