Question
Define a combination reaction.
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$\ \ \ \ \ \ \ \ \text{H}\ \ \ \ \ \text{H}\ \ \ \ \text{H}\ \ \ \ \ \ \text{H}\\\ \ \ \ \ \ \ \ \ |\ \ \ \ \ \ \ |\ \ \ \ \ \ |\ \ \ \ \ \ \ |\\\text{H}-\text{C}-\text{C}-\text{C}=\text{C}-\text{H}\\\ \ \ \ \ \ \ \ \ |\ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \text{H}\ \ \ \ \ \ \text{H}$