... best completes the unfinished statement (or best answers the question) about each passage. In 1782, the bald eagle was chosen as the national bird of the United States because it is a bird of ... there were only 3,000 bald eagles in the entire United States. The reason for the bird's decreasing population was pollution, especially pollution of the rivers by pesticides. Pesticides ... must C. mustn't D. needn't 16. Carl ___________________studied harder; he failed the test again. A. must have B. should have C. could have D. needn't have 17. "Would you...