Final answer:
The sentence 'Where have you ------ all this while?' is correctly completed by adding the word 'been'. This creates a question about the person's recent activities or whereabouts in conversational English.
Step-by-step explanation:
The correct word to complete the sentence 'Where have you ------ all this while?' is 'been'.
So the complete sentence is 'Where have you been all this while?'. The sentence is asking someone about their whereabouts or what they have been doing during a certain period of time. This type of sentence is typically used in conversational English to catch up with someone's activities.
The provided dialogue illustrates a similar conversational exchange where one person is curious about the other's actions during a recent time frame. In the example, the response shows that the person was not alone but was accompanying someone else, indicating her activity during that period.