1. 与 in general
2. 以。。。noun verb object as in 以凉水冲淡溶液。
与 yu have 3 different tones sceond tone , third tone and forth tone and have different meanings.
Of course , it can be used in spoken Chinese.
以 in this sentence means "用" ，but in modern Chinese , we prefer 用 to 以。 用凉水冲淡溶液。
but there are some ancient form of 以 that still can be seen in modern Chinese, and we can't change them. 以命相抵