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XYZ Inc board of directors have (or has) approved the proposal

A lot of responsibility lies on the investigation team’s shoulders

Let them reveal what is the real truth

Earth is bearing the brunt of science’s advancements
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The board of directors of XYZ Inc have/has approved the proposal. A lot of responsibility lies on the investigation team’s shoulders. Let them reveal what is the real truth: Earth is bearing the brunt of the advancements of science.
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Yes. American English tends to use the singular for this type of construction, but if you are thinking of the the board members as acting inidivdually, then you can use have.
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Comments  
The board of directors of XYZ Inc have/has approved the proposal

In the above sentence I can use either of has / have
 BarbaraPA's reply was promoted to an answer.
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