将2个数据帧与多个不同列名的列合并

I need help with a merge(vlookup) problem that I can not solve. I have 2 data frames I would like to merge, in addition they also have different column names. My real datasets have many columns and that why its a hard for me to come up with a solution. I have tried the merge function but I can not figure out how to do it on multiple columns with different names. I would like to explicitly specify the column names using something like:I need help with a merge(vlookup) problem that