12.Many factors lead to land ______, including soil erosion, desertification, and loss of vegetation cover.
(A) acquisition (B) distribution (C) degradation (D) reclamation
18.Had you informed me of the problem, I ______ assistance.
(A) would has provided (B) would had provided
(C) would have been provided (D) would have provided
21.The Supreme Court heard arguments in a case brought by a religious postal worker who says he should not
be forced to work ______ the Sabbath.
(A) at (B) wherein (C) on (D) under