题目

根据短文内容, 从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。How to write a Letter to Parents As a teacher, one of the most difficult parts of your job is working with parents. Writing a letter to parents is one way to do this. If you do it properly, this is an excellent way to communicate when you cannot meet with parents face to face. Put positive communication in the letter, even if you are writing to discuss a problem. Even if it is difficult, you must find this positive spin（言辞）, because it will make the parents more o小华同学骑着一辆自行车在平直公路上匀速运动500m，所用时间为100s，设自行车在行驶过程中受到的阻力为120N，请你解答：（1）自行车行驶的速度是多少？（2）在这段过程中，该同学所做的功率是多少？