Only if: Como utilizar

Hey, guys! Good morning!

Then, I was studying invertion and I have a question about the phrases that use "only if".

When must they be inverted?

For example, I have two sentences in the exercises where the book says they're wrong:

1 - Only if it's convenient she will come.
2 - Only if he wasn't available did she come in.

The reason the book uses to say these are wrong is that the phrases are unnatural. I couldn't understand the general rule, so if someone could help me, I'd be really glad!

Thank you for the help!

Nesta aula, a professora Camila Oliveira ensina como você deve se preparar para fazer uma apresentação pessoal profissional em inglês. O conteúdo dessa aula ajudará você a aproveitar melhor as oportunidades no ambiente corporativo. ACESSAR AULA
2 respostas
Donay Mendonça 23 108 1.6k

Para mim,falta um pouco mais de informação na pergunta.Mas eu diria que a construção,"She will come only if it's convenient" ficaria melhor.

Aguardo mais complementos à pergunta.

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Marcio_Farias 1 24 213
I think you can do it with adverbs such as "Not only ... but also", "Not until", "Hardly (ever)" etc.

"I tell you, on no account did the forum members and users take Hermenegildo's beatifully elaborate explanations for granted."
"Not only did the roof cave in, but also the entire cave."
"Under no circumstance should the children mess with the diamond back rattlesnakes, which freely abound around the area."
"Not until did the group arrive in Obó that... damn, I can't seem to make a continuation for that!"
"Never in Hermenegildo's life had he traveled that far into outer space."
"Never in Hermenegildo's life could he ever thought he could go that far into..."
"Not a single word of consolation did Hermenegildo bother to offer in the case of Biu Jamelão after the latter plunged to his death from as high as 350 meters off the edge of the cliff." (Awkwardly written, but then...)