Question

His friends deserted him. His relatives too did the same. (use not only but also)

Answer 1

$\huge\bold\red{Answer} \checkmark$

His friends deserted him not only but also his relatives too did the same.

Answer 2

$\huge\colorbox{aqua}{Ãn§wer࿐✓ }$

$\pink{ ❐ }$ He was deserted not only by his friends but also by his relatives.

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When using not only $\dots$ but also in a sentence, parallelism should be the goal. It means that the words following both parts of this correlative conjunction (i.e., not only and but also) should belong to the same parts of speech.