On time 和In time的区别
On time及In time都是形容词，意思是准时、按时、没迟到等。但在英文句子的用法及结构中却不一样。
（1）On time：一般用在句子后或最后两个字。On time的用词是当一件事准时发生，事情是按计划而发生的，如︰
eg︰The 11:45a.m. train left On time. 上午11时45分的火车按时出发了。（火车在上午11时45分出发。）
eg︰“I’ll meet you at 7:30 tonight。”“Okay,but please be On time.”“我今晚七点半见你。”“好的，不过请准时。”（第二者提醒第一者別迟到。）
eg︰The conference was very well organized. Everything began and finished On time. 会议安排得很好，所有的事项都准时开始及结束。
eg︰Be on time. Don’t be late. 要准时，別迟到。
（2）In time：英文句子结构是——in time＋动词或某些情況
eg︰Will you be home in time for dinner？你会准时到家吃晚饭吗？（赶得及到家吃饭）
eg︰I’ve sent a birthday greeting card for Jill’s birthday.I hope it will arrived in time before her birthday. 我已经寄了一张生日卡给Jill，希望那张卡会在她生日前准时寄到。（赶得及寄给Jill。）
eg︰I must hurry.I want to get home in time to watch the football final match. 我一定要快。我要准时到家看足球决賽。（赶得及看球賽。）
我们也可说Just in time, 意思是刚好、正好、恰好准时︰
eg︰We got to the station just in time to catch the last train. 我们刚好准时到达车站，及时赶上最后一班火车。
eg︰A child ran across the road in front of my car,but I managed to stop my car just in time.有个小孩冲出马路到我的车前，不过我刚好及时把车停下来。 练习（1）︰填上on time或 in time.
1.The bus was late this morning,it’s usually_____.
2.I like to get up_____to have a big breakfast before going to work.
3.We want to start the meeting_____,so please don’t be late.
4.I’ve just washed this shirt.I want to wear it this evening,so I hope it will be dry_____.
5.The train service isn’t very good. The trains are rarely_____.
6.I nearly missed my flight this morning. I got to the airport just_____.
7.I nearly forgot that it was Joe’s birthday, Fortunately, I remember_____.
8.Why are you never_____？You always keep everybody waiting.
练习（2）︰按照以下情況，造一句使用just in time的句子。
A child ran across the road in front of your car. You saw the child at the last moment.（manage/stop）
I managed to stop just in time.
1.You were walking home without an umbrella.Just after you got home,it started to rain very heavily.（get/home）
2.Tim was going to sit on the chair you had just painted.You said,“Don’t sit on that chair！”so he didn’t.（stop/him）
3.You went to the cinema. You were a bit late and you thought you would miss the beginning of the film. But the film began just as you sat down in the cinema.（get/cinema/beginning of the film）
练习1︰1.on time2.in time3.on time4.in time 5.on time6.in time7.in time8.on time 练习2︰1.I/We got home just in time. 2.I stopped him just in time.
3.I/We got to the cinema just in time for the beginning of the film. 记住, 英语的介词的引申用法都和原义有关, in 是在里面,在内. 那么在时间范围内,就是没晚,及时的意思. on是在...上,是在边界上, 确切的点上, 所以是准时的意思.