Very little is going on. It's four measures in the key of G for the first clarinet chair. The first measure is a quarter rest followed by two slurred eighth notes and a half rest. This changes in the remaining three measures to the same eighth note figure (G slurred to E) in the first beat followed by a quarter rest and a half rest. The notes should be played loud — fortissimo.
A second voice (below) may be added later but in these four measure the second voice has four whole rests and doesn't play.
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