virtual front time of a lightning impulse

例句：

1. 1. The virtual reality game is very popular among young people.
   虚拟现实游戏在年轻人中非常流行。
2. 2. She created a virtual world for her children to play in.
   她为孩子们创造了一个虚拟世界供他们玩耍。
3. 3. The virtual assistant can perform many tasks that would otherwise require human intervention.
   这个虚拟助手可以执行许多原本需要人工干预的任务。