1."They were impatient <b>at</b> the delay"<br/> "They were impatient <b>because</b> of the delay"<br/><br/>2."She was delighted <b>at</b> the result"<br/><br/> "She was delighted <b>because</b> of the result"<br/><br/>3."He was happy <b>at</b> his promotion"<br/><br/> "He was happy <b>because</b> of his promotion"<br/><br/>Which preposition are used more commonly by natives when describing the cause of something?<br/><br/>Thank you