तब

In a sentence

• अगर तब तक बारिश नहीं रुकी, तो हम बाद में निकलेंगे।

  If it doesn't stop raining by then, we will leave later.

  In this sentence, 'तब तक' refers to a specific point in time until which something is expected to occur.

• तब हमें समझ आया कि हमने गलती की थी।

  Then we realized that we had made a mistake.

  Here, 'तब' is used to refer to a specific moment in the past when the realization occurred.

• तब तुम कहा थे जब मुझे तुम्हारी ज़रूरत थी?

  Where were you when I needed you?

  In this instance, 'तब' refers to a specific past time correlated with the speaker's need.