题目

阅读短文，从每题所给的四个选项 (A、B、C和D) 中，选出最佳选项。 The US teenager Thomas Cheatham had plannedto study Latin during his time at Hebron High School in Texas. But when helearned that the school district was going to offer a Mandarin class, hequickly changed his mind. I thought Mandarin would be more useful than Latin, said Cheatham, who is now in his second year of studying the language. He speaks Mandarin to order food at Chinese restaurants and can read social media posts from his Chinese-speaking friends. While it's a difficult language to master, the hi在水平地面上，小明用100N的水平推力推动重为80N的箱子，8s内前进了6m，在这个过程中木箱所受的重力对木箱做的功为    J，小明对木箱做功的功率为    W．