Mark the letter A, B, C or D to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.
31. Coal is limited and it can be replaced by renewable sources.
A. finite B. abundant C. effective D. alternative 32. Solar energy is plentiful and it can be replaced easily.
A. a few B. limited C. abundant D. harmful
33. Coal, oil, natural gas are all non-renewable energy sources, so they can be used up.
A. ran out of B. ran over C. ran up D. ran to