some 后接可数名词或不可数名词。

You use some to refer to a quantity of something or to a number of people or things, when you are not stating the quantity or number precisely. 一些

当你没有准确地陈述数量或数字时，你可以用some来指代某物的数量或一些人或事物。

例1：

Robin opened some champagne.

罗宾打开了一些香槟酒。

例2：

He went to fetch some books.

他去取来了一些书。

several 后接可数名词

Several is used to refer to a number of people or things that is not large but is greater than two. 几; 一些

several用来指数量不大但大于2的人或物的数量。

例1：

I had lived two doors away from this family for several years.

我与相隔两户的这家人做了几年的邻居。

例2：

Several blue plastic boxes under the window were filled with CDs.

窗子下面的几个蓝色塑料盒子里装满了激光唱片。

美国英语母语人士点评：

Several is three or more; some can imply any number, usually more than one.

several是指三个或更多;some可以指任何数字，通常不止一个。