I've forgotten what the firm he works for is called.
我已经忘记他所在公司的名称。
Have you forgotten about that money I lent you last week?
你忘记上星期我借给你的那笔钱了吧？
I'd forgotten the keys, which didn't help matters.
我忘记带钥匙了，这让情况更糟。
Are you sure you locked the gate? You could easily have forgotten.
你肯定锁上大门了吗？你很可能是忘了。
Oh sugar! I've forgotten my book!
哎呀！我忘带书了！