Here are the answers to your questions:
Question 16: The captains of the high-school softball team are pitcher, Marisa Martino, outfielder, Rachel Morrison, and catcher, Lisa Fiore. (This sentence requires semicolons instead of commas because it lists items that contain internal commas.)
Question 17: Last week, Brian read "The Fall of the House of Usher" before his shift at the ice cream shop. (The quotation marks correctly enclose the title of the work without surrounding other parts of the sentence incorrectly.)
Question 18: A word that receives the action of the verb (This is the correct definition of a direct object.)
Question 19: The road is bumpy, curvy, and long. (This sentence contains coordinate adjectives since all the adjectives are of equal importance and describe the road.)