to calculate the time, first look at the speed of music: one minute (in seconds) = how many beats. Secondly, look at what kind of rhythm it is: 2/4. 4/4。 (Take quarter notes as a beat). Finally, divide eight beats by how many beats per minute (in seconds) to get the time of eight beats. Take the broadcast exercise as an example. One eight is about 7 seconds long, and eight eight beats is 56 seconds.

Eight beats means four beats is four beats, and eight beats is eight beats.