ACT English--help me with IDIOM!!!

<p>hi, i am taking the act on sat and i was wondering if anyone can help me and give examples of "incorrect idiom" or however you say it. i know what idiom IS, i just need some commonly tested examples on the ACT. thanks :)</p>

<p>from the ACT official book:</p>

<p>Their idea was demonstrated often when my elderly relatives, who took pride in remiding younger folk of their "Korean age."</p>

<p>A. NO CHANGE
B. by
C. while
D. as if</p>

<p>by (10char)</p>

<p>thx...any other$ examples. particularly the really hard ones?</p>