单选题：Questions 19--33·Read the article below about the importance

Questions 19--33
·Read the article below about the importance of writing job descriptions.
· Choose the best word or phrase to fill each gap from A, B, C, or D on the opposite page.
· For each question 19--33, mark one letter (A, B, C, or D) on your Answer Sheet.
· There is an example at the beginning, (0).

根据以上材料，回答第（19）处的填空。