Can you explain why you were so late?
你能解释一下为什么迟到了吗?
How come it has taken you so long to reply to my email?
你怎么这么久才回复我的邮件?
I don’t understand why you never finished the work on time.
我不明白你为什么从来没有按时完成工作。
Do you expect me to believe you did this by yourself?
你以为我会相信这是你自己干的吗?