Question

The gadget ______________ died out as quickly as it had come up.

Answer 1

Answer:

had.

the gadget had died out as quickly as it had come up

Answer 2

The gadget had died out as quickly as it had come up.

• 'Had' is a main form of a verb.
  
• It is the past tense form as well as the past participle form of the verb, 'have'.
  
• The verb 'had' is often used instead of the conjugation, 'if'.
  
• Therefore, it will be: The gadget had died out as quickly as it had come up.

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