The grades were hidden by the teacher. They may have chosen to hide the grades temporarily to allow for a more controlled and organized way of distributing them to the students. This could also be a way to prevent any unnecessary stress or competition among the students before they receive their grades. Ultimately, the decision to hide the grades was likely made by the teacher in order to manage the grading process more effectively. **

An HID keyboard is a type of keyboard that uses the Human Interface Device (HID) protocol to communicate with a computer. This protocol allows the keyboard to be recognized as a standard input device by the computer, enabling it to send keystrokes and other commands. HID keyboards are commonly used in computers, laptops, and other devices that require user input. **

A HID (Human Interface Device) keyboard is a type of keyboard that connects to a computer using the USB HID protocol. This protocol allows the keyboard to communicate with the computer as a standard input device, enabling it to send key presses and other commands to the computer. HID keyboards are commonly used for typing and controlling computer functions, and they are compatible with a wide range of devices and operating systems. **

An HID-compliant touchscreen refers to a touchscreen device that meets the specifications outlined by the Human Interface Device (HID) standard, ensuring it can communicate with a computer system using standard protocols. On the other hand, an HID-compatible touchscreen may not fully adhere to the HID standard but can still function with a computer system using generic drivers or software. In essence, an HID-compliant touchscreen is designed to work seamlessly with a wide range of devices, while an HID-compatible touchscreen may require additional configuration or software to function properly. **

Contactless payment works by using radio-frequency identification (RFID) or near-field communication (NFC) technology to enable secure transactions between a contactless card or mobile device and a contactless-enabled payment terminal. When a contactless card or device is tapped or waved near the terminal, the necessary payment information is transmitted wirelessly, allowing for a quick and convenient transaction without the need to physically swipe or insert a card. Contactless payment is typically used for small purchases and offers a faster and more hygienic alternative to traditional payment methods. **

A contactless key is a type of key that uses radio frequency identification (RFID) or near-field communication (NFC) technology to allow access to a building or vehicle without the need for physical contact. This type of key typically comes in the form of a card or fob that can be waved near a reader to unlock doors or start a vehicle. Contactless keys are convenient and provide a hands-free way of accessing secured areas or operating vehicles. **

Contactless electric cars are vehicles that can be charged wirelessly, without the need for physical cables or plugs. This technology uses electromagnetic fields to transfer energy from a charging pad on the ground to a receiver on the vehicle, allowing for convenient and efficient charging. Contactless electric cars are a promising development in the electric vehicle industry, as they offer a more seamless and user-friendly charging experience for drivers. This technology has the potential to make electric vehicles even more accessible and convenient for consumers. **

The opposite of contactless is "contact." Contactless refers to a method of payment or interaction that does not require physical touch, while contact involves physical touch or interaction. For example, a contactless payment is made by waving a card or using a mobile device, while a contact payment involves inserting a card or using cash and physically touching a payment terminal. **