The definitions of friend, best friend, and acquaintance can vary depending on individual perspectives and cultural norms. Generally, a friend is someone with whom you have a mutual bond of affection and trust. A best friend is typically someone with whom you share a deeper level of emotional connection, trust, and understanding. An acquaintance is someone you know casually, but with whom you may not have a close or personal relationship. While these definitions provide a general understanding, the specific meanings of these terms can differ from person to person. **

The acquaintance is confused by the sudden change in the protagonist's behavior. They are surprised by the protagonist's sudden withdrawal and lack of communication, which is out of character for them. The acquaintance is also puzzled by the protagonist's refusal to explain their actions, leaving them feeling bewildered and concerned about the situation. **

It is difficult to determine if your acquaintance is jealous without more context or specific behaviors to consider. Jealousy can manifest in different ways, such as making negative comments, acting distant, or showing passive-aggressive behavior. It may be helpful to have an open and honest conversation with your acquaintance to address any concerns or misunderstandings. Observing their reactions and communication patterns can also provide insights into their feelings. **

A strange acquaintance is someone you have met in an unusual or unexpected way, and with whom you have a peculiar or unconventional relationship. This person may have unique quirks or behaviors that make them stand out, or they may have an unusual background or set of interests. A strange acquaintance can add an element of unpredictability and intrigue to your social circle, and can often lead to memorable and interesting interactions. **

I'm sorry, I cannot provide an answer to that question as I do not have information about the acquaintance's possession of planarians. **

I cannot determine if your acquaintance is a sadist without more information. Sadism is a complex psychological trait characterized by deriving pleasure from inflicting pain or humiliation on others. It is important to consider their behavior and how they interact with others to determine if they exhibit sadistic tendencies. If you have concerns about their behavior, it may be helpful to seek advice from a mental health professional. **

A dust acquaintance is a term used to describe someone who you only see occasionally or rarely, and with whom you have a superficial or fleeting relationship. This type of acquaintance is not someone you have a close or meaningful connection with, but rather someone you may run into from time to time in passing. The term implies that the relationship is fleeting and insignificant, much like dust that can easily be brushed away. **

A casual acquaintance is someone you know or have met briefly, but with whom you do not have a close or deep relationship. This person may be someone you see occasionally at social events, work, or in your community, but you do not have a strong personal connection with them. Casual acquaintances are typically more superficial in nature and do not involve a significant level of emotional investment or intimacy. **