What is the relation of the sign of the charge on the charging body to the sign of the charge on the charged body when the charging is by contact

Charging by conduction involves the contact of a charged object to a neutral object ...

Explanation:

Suppose that a charged aluminum plate is touched to a neutral metal sphere, the neutral metal sphere becomes negatively charged because of the results of being contacted by the charged aluminum plate. A charged metal sphere is touched to the highest plate of a neutral needle measuring instrument, the neutral measuring instrument becomes charged because of the results of being contacted by the metal sphere. For example, a student standing on an insulating platform touches a negatively charged Van de Graaff generator, the neutrally charged student becomes charged. This is due to the contact made with the Van De Graaff generator which is negatively charged.