writing question, should be pretty easy

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1

<p>I was working in the blue book and I can't figure out why this answer is correct...</p>

<p>Marie and Pierre Curie discovered radium but refused to patent the process they [used nor otherwise profiting] from the commercial exploitation of radium.</p>

<p>correct answer: had used or otherwise to profit</p>

<p>explain please? and obviously, I'm not that great at writing..so any tips would be GREAT!! tips for CR or math would also be appreciated :)</p>

2

<p>Since they had already completed it in the past, the past perfect tense 'had used' is used in the sentence.</p>

3

<p>yeah I understood that part, but the "to profit" is throwing me off because it isn't conjugated?</p>