once和when引导从句时的区分

1. Once I think about going back to school, I feel depressed.

2. When I think about going back to school, I feel depressed.

我觉得两个句子都可以用，第一个的意思是一旦想起要回到学校，我就感到焦虑。

第二个：当我想到我要回到学校，我就感到焦虑。

不知道两个句子哪个是对的，哪个是错的，希望有老师解答一下。

这二个句子的主从句都是一般现在时，表示的是习惯意义。此时用once 和when(ever)都是正确的。这种从句其实是时间状语从句兼有条件的意味。换用if引导从句，意思基本不变。夸克称这种从句实际上条件和时间从句揉合在一起了（neutralized).

曹荣禄 -

擅长：动词用法,句法问题 | 采纳率 82% | 回答于 1秒前

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其它 1 个回答

陈才 - 英语教师 1秒前

擅长：中考英语,词法问题

(1)Once I think about going back to school, I feel depressed.

=If I think about going back to school, I feel depressed.

(2)When I think about going back to school, I feel depressed.

=As soon as I think about going back to school, I feel depressed.