A basal thermometer is designed to measure the slight temperature changes that occur during a woman's menstrual cycle, particularly around ovulation. It is more sensitive and accurate than a regular fever thermometer. On the other hand, a fever thermometer is used to measure higher body temperatures that indicate fever or illness. Fever thermometers are typically less sensitive and have a wider temperature range compared to basal thermometers. **

It ultimately depends on personal preference and what you would use more often. If you find yourself needing a pen frequently, then a pen would be the more practical choice. However, if you are someone who frequently loses or misplaces keys, then a keychain might be the more useful option. Both items can be functional and stylish accessories, so it's really a matter of what you would get the most use out of. **

No, the outdoor thermometer does not display a weather forecast. It simply measures and displays the current temperature outside. Weather forecasts are typically provided by meteorologists or weather stations based on a variety of factors such as temperature, humidity, wind speed, and atmospheric pressure. The outdoor thermometer only provides a snapshot of the current temperature at a specific location. **

A fever thermometer is specifically designed to measure body temperature and is typically more accurate in detecting slight changes in temperature. It usually has a narrower temperature range compared to a regular thermometer, which can measure a wider range of temperatures. Additionally, fever thermometers often have features like flexible tips for comfort and safety during oral, rectal, or underarm use, while regular thermometers may not have these specialized features. **

Without further information or context, it is difficult to determine if the keychain is broken. If you can provide more details about the issue with the keychain, such as a description of the damage or malfunction, I would be happy to help assess the situation. **

There are many different bicycle thermometers available on the market, so the best one for you will depend on your specific needs and preferences. Some factors to consider when choosing a bicycle thermometer include the type of display you prefer (digital or analog), the mounting options available, the temperature range it can measure, and any additional features such as a built-in compass or backlight. It's also important to consider the durability and reliability of the thermometer, especially if you plan to use it for outdoor activities. Researching and comparing different models will help you find the best bicycle thermometer for your needs. **

To mount a compass attachment onto a compass, first ensure that the attachment is compatible with the specific model of compass. Then, carefully align the attachment with the designated mounting area on the compass. Depending on the design, you may need to use screws, adhesive, or other fastening methods to secure the attachment in place. It's important to follow the manufacturer's instructions and make sure the attachment is securely mounted to ensure accurate readings. **

The correct grammar for "outdoor thermometer in the car" is to use the adjective "outdoor" to modify the noun "thermometer," and the prepositional phrase "in the car" to indicate the location of the thermometer. This construction follows the pattern of adjective + noun + prepositional phrase. **