Alice received an invitation from her boss,it came as a surp

Alice received an invitation from her boss,it came as a surprise
上面的句子要把it换成which,which肯定不错了,据说是用了it后就成两单独的句子的,那么it前面再加上and语法上通不通呢,如果像I like swimming ,John likes singing.错不错呢.

1.换成which,的确需要加逗号,这里就变成了一个定语从句.which代指的是前面这句话的意思,也就是艾莉丝收到了老板的邀请函这件事,对于艾莉丝来说是一个惊喜.
2.如果非要用and it came as a surprise,这样语法上也是对的,但是这就变成了and连接的两个并列从句,大致的意思是一样的,但是语法上就完全是两个概念了.
其实,语法这东西,如果应付考试,建议还是买本语法书,系统的看一下,如果只是平时应用,那就无所为了,因为平时老外是不会介意你的语法是否有错误了,关键是能让别人懂你!