<p>Chess players find that playing against a computer is helpful (to improve) A (their) B skills, (even though) C no chess-playing computer has yet (won) D a championship.</p>
<p>His love of politics (led) A (him) B to volunteer in local campaigns (as well) C as (a job) D
in a government office in the state capital.</p>
<p>Now that Michiko (finished) A the research, she feels (reasonably confident) B (about writing) C her paper on the (rise of) D the progressive movement in the United States.</p>
<ol>
<li><p>A. improve. I think helpful to is unidiomatic</p></li>
<li><p>d. job needs parallel structure… led him to volunteer. as well as…“action”</p></li>
<li><p>a. it should be “has finished”, because the research is affecting a present action? I’m not sure aobut htis one</p></li>
</ol>
<p>I’m not convinced that A is incorrect in the first example, but I’m not sure. Otherwise I definitely agree. In the last example “has finished” is correct because that is the present perfect tense, which is English shows that an action has been completed but you’re looking at it from a present state of reference. [This is also called having perfect aspect, thank you Wikipedia!]
Compare: Michiko <finished> the research and then wrote her paper.
Now that Michiko <has finished=“”> the research, she can write her paper.</has></finished></p>