Writing sentence question

Test Preparation SAT Preparation
1

<p><em>Also supported</em> by the commision <em>was</em> the proposed health clinics and the proposed <em>center</em> to distribute information <em>on job-training</em> oppurtunities.</p>

<p>was is wrong
I'm guessing the answer is were? Why? Do I have to find what "supported" (gerund, I dunno what this is) refers to for this question, or any with phrases as subjects?</p>

2

<p>“was” needs to be “were” because “clinics” and “center” are both subjects of the verb.</p>

3

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<p>The passive voice is not considered erroneous on the SAT.</p>