I went to bed after I finished my homework.同义句转换I（）（）to bed after I finished my homework

I（was）（going）to bed after I finished my homework
I（was）（planning）to bed after I finished my homework
I（was）（preparing）to bed after I finished my homework
I（look）（forward）to bed after I finished my homework

题目错误！

应该是：
I went to bed after I finished my homework.

=I finished my homework before I went to bed.

=I（didn't go) to bed (until) I finished my homework.

我们以前常做的思路是 I （）（）to bed until/before I finished my homework。。。