The correct answers are Captain Thunder doesn't run as fast as Lightning Lad., Lightning Lad is as strong as an ox., and Lightning Lad doesn't fight as bravely as his partner.

Remember to use the base form of the adjective or adverb between "as...as". "Harder" is a comparative adjective, and "highly" is an adverb that means "very much" (like "highly recommended"), not a measure of physical height! The adverb for physical height is just "high".