Band-4 listening headphones are usually equipped with two 5th batteries. Individual headphones with radio function will have different models and batteries, usually No.5 or No.7 batteries. According to the shape, the thicker battery is the No.5 battery, and the thinner battery is the No.7 battery.

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CET-4 is a compulsory examination in universities. However, the listening style of the exam has changed. Don't broadcast in the classroom during the college entrance examination. Individuals should prepare their own listening headphones and use them to receive broadcast signals to test listening problems.

If the headphones are working properly, you can start tuning the channel. Press the radio station selection on the main keyboard to increase or decrease, and you can find your own campus radio station. Generally speaking, the campus platform is the frequency specified in CET-4. Different schools should accept different frequencies. If you don't know how much money there is, you can ask the teacher.

You'd better prepare the battery for the exam, or it will be too late when you get to the classroom and find that the battery is dead. After using the earphone, it is best to take out the battery and seal it. Otherwise, it is easy to consume electricity, and there will be water vapor in the earphone, which will corrode the battery.