151 is a first degree chord and 535 is a fourth degree chord. According to the relevant information, the first chord is 135, the second is 735, the third is 635, the fourth is the 535 chord, the most typical one is "Excuse", the C chord is composed of 1, 3, 5 The major triad formed by the superposition of three tones is a major I-level main chord and a minor-level III chord. The C chord is the 1st degree chord in the key of C major, which is used to clarify the tonality. Songs all start in a major key and end in a major key. Use the main chord as little as possible in the middle of the song, which always gives people a sense of ending, and the progression of the music will also be very hard. Fingering instructions: The index finger of the left hand presses the 2nd string and the 1st fret, the middle finger presses the 4th string and the 2nd fret, and the ring finger presses the 5th string and the 3rd fret. .