Why silent for a period of time

Why silent for a period of time wait for a period of time. We lived in Beijing for a period of time. for a long period of time可以用什么替换? thanks!I will try waiting for a period of time. over a period of time Aftre the death of his wife ,for a long period of time,he_si 英语翻译 over a period of time A period of time 用于什么时态 over a long period of time 是a period of time 还是times? you owe me a period of time