He has been dead for three years.
He has been dead since three years.
It is three years since he died.
这三句话，正确吗？1，2句中的for 和since在这里是一样的用法 吗？
请指教了!
混了
參考答案:现在完成时常和since引导的短语或从句，或由for引导的表一段时间的短语连用。
第一句是对的。for接一段时间，since接一个时间点。
因此第二句He has been dead since three years.应该在后面加上ago，表示一个时间点。
第三句应该是现在完成时，It has been three years since he died.