一般来说，因为它是靠感应重心变化来实现前后左右的，所以主要看自己能否控制好。这类车，比较明显的区分是大轮和小轮。大轮安全性不好，它轮子高过脚面，挡住了侧面逃逸的可能性，往前有把手杆，一旦控制不好，往前冲，那二次伤害的可能性就非常大了。大轮车的最高速度也比较高，玩high了比较危险，但有人就喜欢这种刺激感。小轮好很多，安全性高。轮子小，两侧是开放式的，旁边就能跳下来，最多把车摔了，人很少会出事儿。像乐行的那款车最高时速也就是15km，如果体重轻的小朋友骑，可以自己感应到体重，降低最高时速，比较安全些。
1. They came to China in 1990.(变一般疑问句)
Did they come to China in 1990?
2. I was ill for two days last week? (同上)
were you ill for two days last week?
3. The twins go to school on foot every day. (同上)
DO the twins go to school on foot every day?
4. She washed the clothes last Sunday. ( 变否定句)
She didn't wash the clothes last Sunday.
5. She is going to shopping tomorrow. (变否定句)
She isn't going to shopping tomorrow.
6. My mother likes her students. (变一般疑问句)
Does My mother like her students?_________________________________
7. Do you watch TV on Sunday? (用last Sunday 改写成过去时态的句子)
Did you watch TV on Sunday?
8. Wei Hua bought a new pen yesterday. (变否定句)
She diidn't buy a new pen yesterday.
9. We had a meeting the day before yesterday. (变一般疑问句)
Did you have a meeting the day before yesterday?
10. They had a good time last Sunday.
Did the twins have a good time?
