Implied effect refers to the use of implicit and abstract indirect methods to influence people's psychology and behavior under the condition of no confrontation, thereby inducing people to act or accept certain opinions in a certain way, so that their thinking, behavior and The hinter's expectations are consistent. According to the above definition, which of the following options have no implied effect? ['The classmates are still discussing the topics in the classroom. The teacher who is teaching stops and the classroom is silent.', 'Grandma Zhang in her 70s kept mumbling, "My grandson is coming back soon", not long after, her grandson came back to visit her.', 'In the forest, the old Orion walked silently, everyone followed closely.', 'Since the class teacher praised Xiaohong for her fast learning progress at the class meeting, Xiaohong has worked harder.']