问题
多选题
| 如图所示，一弹簧振子在B、C间做简谐运动，O为平衡位置，BC间距离为10cm，从B运动到C的最短时间为1s，下列说法正确的是（ ） A．从B到C振子作了一次全振动 B．振动周期为2s，振幅为5cm C．经过两次全振动，振子通过的路程是20cm D．振子从B点开始，经3s位移是30cm  |
答案
BD
搜题请搜索小程序“爱下问搜题”
| 如图所示，一弹簧振子在B、C间做简谐运动，O为平衡位置，BC间距离为10cm，从B运动到C的最短时间为1s，下列说法正确的是（ ） A．从B到C振子作了一次全振动 B．振动周期为2s，振幅为5cm C．经过两次全振动，振子通过的路程是20cm D．振子从B点开始，经3s位移是30cm |
BD
| 从下面方框中选择适当的选项填入短文中，使短文通顺，完整。选项中有两个选项是多余选项。 | |
broken down. Just then a poor man named Robert came. He was on his way back home from work as usual. The lady wondered, "Is the man going to help me?.He looks very 2 and hungry. " But to her surprise, he stopped and said with a smile, "What's wrong madam?" The lady told him what was happening. After forty minutes, the car was at las't'fixed by Robert. The lady wanted to pay him. "No, that's 3 , madam. " He said, "I was just helping someone in need. If you really want to pay me back, I hope whenever you see someone in 4 , please give him a hand. " A few minutes later, the lady saw a shabby (破旧的) house by the road. She 5 Robert's words, so she stopped. The hostess warmly asked her in. The lady could see that was a 6 family and they needed help. When the hostess was making tea in the kitchen, the lady 7 500 dollars on the table and went away quietly. Robert came home later than 8 ,thinking how hard their life was. Their baby was to be born the next month 9 there wasn't enough money. His wife went up to him, gave him a kiss and said 10 , "Don't worry, dear! Everything is going to be all right. A stranger has helped u.s out. " Let's always be ready to help others because helping others is helping ourselves. |