in time, on time 和 in good time 这三个短语的意思是否相同？
这三个短语的意思是不相同的。in time 的意思是“及时”（by the due time），“终有一天”“最后”“迟早”或“终于”（eventually, ultimately, at some unspecified time in the future）：
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I wish you would come in time. 我希望你及时赶到。
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The journey may seem long and tedious, but we shall get there in time. 旅行似乎是漫长而乏味的，但是我们将及时赶到那里。
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We were in time for the train. 我们及时赶上了火车。
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We got to the station just in time to catch the bus. (DAI) 我们及时到达车站, 赶上了公共汽车。
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Will you be home in time to see the children before they go to bed? (LDCE) 请你在孩子们睡觉之前及时赶到家照料一下他们好吗？
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In time, all Sam's money was paid back in this way. (New Concept English, Book 2, L. 45) 最后, 萨姆所有的钱都以这种方式被还了回来。
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If you keep on, you will succeed in time. 如果你坚持下去，总有一天会成功的。
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In time, all this will be forgotten. 到时候这一切都会被忘记的。
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The candle-light will in time go out of itself. 烛光到时候会自行熄灭的。
on time 则是指“准时”“准点”“正点”(at the time required, punctually):
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The train arrived on time. 火车正点到达。
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Please be here tomorrow on time. 请明天准时到这儿来。
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My employer will confirm that I was there on time. (NCE 2, L.87) 我的老板可以证明我是准时上班的。
in good time 与 in time 的意思大体相同。但是,有时候还表示“提前”(sooner than necessary; before a set time)的意思,见 time(in good time)。
"Was the train late today?" "No, it's ____.
If you keep on, you'll succeed ____.