请准时到校用英语：Please get to school on time,
必须准时到校的英文：Must come to school on time必须：must; have to; be obliged to; necessary gotta，准时：punctual; on time; on schedule ;到校：get to school; come to school
on time的用法例句如下：
1、We shall be landing in Paris in sixteen minutes, exactly on time.我们将于16分钟后准时在巴黎降落。
2、Planes are crowded, airlines overbook, and departures are almost never on time.机拥挤不堪，航空公司超额售票，起飞时间几乎从未准点过。
3、The car was not returned on time, then was reported stolen.这辆车没有按时归还，然后就报失了。
4、He made a concentrated effort to finish the work on time.他全力以赴以按时完成这项工作。
5、Please make every endeavour to arrive on time.请尽全力按时到达。
6、In her haste to complete the work on time, she made a number of mistakes.她急急忙忙想按时完工，结果出了不少错。
must的常见用法例句如下：
1、You must have noticed how tired he sometimes looks.你一定注意到他有时候显得特别疲惫。
2、"His memory must be completely back, then?" — "Just about."“这么说，他的记忆一定是完全恢复了?”——“差不多。”
3、There must be any number of people in my position.一定有很多人处在我这种境况。
4、 I must have driven past that place thousands of times.我得有上千次开车经过那里。