In this case, 差（一）点 would be a better translation than 几乎 for "almost".
Chinese speaker here. 差點 adds more emotion as if you feel bad that you just missed something. 幾乎 is more neutral and just states the fact that you missed something, but you aren't necessarily making a big deal out of it.
Why is 了 in this sentence?
I thought it was to mark the past tense of forget, or "forgot" 忘记 vs 忘记了
It marks a completed action, but this action didn't happen (it just almost happened) so it wasn't completed... I didn't use 了 and still got it right for what it's worth.
I was wondering the same, as the previous sentence 'His father almost forgot to take money with him' was without 了.
Why 忘记 and not just 忘?
You can say 忘记 or 忘了 here.
the same question. I hope somebody will answer
I don't think that it's common for natives to use ''几乎'' in a sentence. Plus I am one, and i've never heard of any of my family say that.
Can you elaborate more on this? <3
I think "了" can be also placed before ”她”
I omitted 了
Sometimes in Duolingo, 了 at the end is accepted, as in 有人偷我的东西了 (I've done it before, it is accepted!) Why isn't "我几乎忘记他的生日了" accepted?
The first sentence there means "Someone stole my things"