<ol>
<li>Throughout the history of science there have been periods</li>
</ol>
<p>(with revolutionary thinkers questioning)A</p>
<p>OR</p>
<p>(when revolutionary thinkers questioned) B</p>
<p>I literally don't understand why is B correct, It is awkward.
2. By the end of 1945, Alice, thirty years old but already [an expert in the field of family dynamics, had begun writing] her memoirs</p>
<p>A. [an expert in the field of family dynamics, had begun writing]
C. as an expert in the field of family dynamics, began to write</p>
<p>Why A is correct? i thought the usage of past tense is grammatically correct. If u use past perfect, i won't make any sense. Because it will mean that Alice had started from a point before 1945 to the end of 1945?</p>
<ol>
<li><p>“Awkward” is not an SAT grammar rule. </p></li>
<li><p>“By [a time]” in the past requires past perfect.</p></li>
</ol>
<p>‘Have been’ would mean in the past, so B fits</p>
- "When" ALWAYS refers to a time. Vice versa, when you have a time "period" (like it says in the question), it is best to say "period when...". This is just a grammar rule that should be memorized. Also, unrelated, "where", ONLY and ALWAYS refers to a place. (i.e. one shouldn't say "during the Middle Ages where...", but should rather say "Middle Ages when..."
- As marvin100 said, "By [date]", or "By the time..." requires the past perfect. The past perfect is "had [past participle]. In this case, the past tense is "began" (which is incorrect) and the past perfect is "had begun" (Note: NOT "had begAn").
Rule of thumb: The past perfect tense PRECEDES the past tense, and is used to describe things that happened before a second action. (i.e. “He had already begun typing when the others arrived.” The action of beginning to type precedes their arrival.)