1、I think the sixteen youngers aren't allowed to drive,because there aren't calm in that time of time.
2、I think the students shuoldn't be allowed to put on earrings.
3、This question have discussed in yesterday meeting.
4、She pleased someone repairing her bike yesterday.
5、这个题目不懂,我的理解是：如果学生们（被）允许和朋友一起做家庭作业,他们说话而不做家庭作业.If the students are allowed to do homework with their friends,they are talking rather than doing their homework.
希望能帮到你.