Hi, I think you just need to look at the objects carefully and decide if the subject or subjects are sharing one object, or if each has their own object.
#1 could really go either way. If you are talking about business as company, then it would be plural. If you are talking about business as a way of making money, I think singular would work.
In #2, if reading and writing are separate skills, then use the plural verb. If reading and writing are taken together to mean “literacy”, then you could use the singular. In this case, I would probably use the plural.
In #3 if they each have a plan, use the plural; if they are sharing the same plan, use the singular.
#4 is similar to #3 - do they share one list or each have their own?
#5 is pretty clearly plural: these two subjects can never really be thought of as a unit.
Every mentoring is up to the good mark, I still think ‘Bonychat’ needs to see the
Barron’s TOEFL suggestion book where the writer indicated more elaborately at chapter of ‘Countable and uncountable’ nouns.
I am afraid that I have no online link at this moment about Barron’s. I always prefer hard copy with authenticated sources though on line is now more convenient if it is authenticated.