Directions: Beneath each of the following sentences there are four choices marked A, B, C and D. Choose the one answer that best completes the sentence.

25.   Researchers are working on treatments that lengthen the life time of mice _____ 50% .

A.     of                           B. by                           C. for                           D. at

26.   Learning that my mother was playing the word game against _____, I bought a computer for her to play against.

A.     her                          B. me                           C. itself                        D. herself