There are several different types of thermometers, including digital and glass (mercury) models.  The most common way to take a temperature for an older child or an adult is to place a digital or glass thermometer underneath your tongue to measure your body’s heat, but there are several other thermometers that use alternate methods for temperature taking.   Digital thermometers can be used orally or rectally (see below) or under the armpit (though this reduces the accuracy of the reading).  The thermometer will beep when the reading is complete, and the temperature displays on a screen.  Tympanic thermometers are used inside the ear canal, and they measure temperature with an infrared light. The downside to this style of thermometer is that a buildup of earwax or the shape of an ear canal can skew the accuracy of the reading.  Temporal thermometers use an infrared light to measure the temperature. These thermometers are great because they are quick and least invasive. To use this type of thermometer, you slide the thermometer from the forehead to the temporal artery, right above the top of the cheekbone.  It can be difficult to master proper placement, but taking several readings can improve the accuracy of the reading.  Pacifier thermometers can be used for babies.  These are similar to oral digital thermometers, but perfect for babies who use pacifiers. The peak reading is displayed when the temperature is measured. After selecting a thermometer, take your temperature according to the method that the thermometer is made for (either orally, in the ear, on the temporal artery, or rectally for a child (see below). If you have a fever above 103 °F (39 °C), you have a baby over 3 months with a fever over 102 °F (39 °C), or you have a newborn (0-3 months) with a fever over 100.4, call the doctor immediately. The most accurate way to take a child’s temperature is through her rectum, but you should use extreme caution so that you do not perforate the child’s bowel.  The best thermometer for rectal temperatures is a...

TL;DR in Chinese:
市面上有许多种温度计，有电子温度计也有水银温度计等等。 不管温度计是入口的、耳式的、非接触的或者儿童用的等等，选择了合适的温度计后，按照其使用方法测量体温。 直肠测量是小孩子测量体温最准确的方法。 如果体温并不是特别高，比如成年人或者6个月以上的孩子的体温在39度以下，那么还是顺其自然比较好，不建议特意退烧。