Confused with writing question in Jan QAS

Test Preparation SAT Preparation
1

<p>I've been pondering over this one writing question and I still don't get it:</p>

<p>In 1988 a Soviet icebreaking ship (a)(helped free) three gray whales that (b)(had become trapped) in the Arctic ice after they (c)(had swam) into the coastal waters of Alaska (d)(to feed).</p>

<p>Why in the world is the answer c? Does it have to be "swam" instead of "had swam" and why?</p>

2

<p>“had swam” should be “had swum” i believe.</p>

<p>scroll down the the Past Perfect Tense:
[Writing</a> English](<a href=“http://www.writingenglish.com/cverbs/swim.htm]Writing”>Writing English)</p>

3

<p>Wow, I knew that but would never have thought of that being the reason it was wrong. Thanks!</p>