有一读者问： 请解释下面两句中let there be的用法：
(1)Let there be food for everyone.
(2)Let there be no waste of time.
Let there be...常用以表示迫切的愿望或需要，比较正式，再如：
(3)Let there be roses and sparkling champaigne.
(4)Please God, don't let there be a train crash.
请解释Let there be...
