用于陈述的转折
示例
A：You mean you failed the exam?
B：Actually, it is not the case! Let me explain.
A：你说你考试不及格？
B：事实上不是这样的，我来解释。
A：No one knows how old she is.
B：Well, actually, yesterday was her 50-year-old birthday.
A：没有人知道她多大了。
B：嗯，实际上，她昨天刚过了50岁生日。