a. Explain the differences between servos and servi in the following sentences. b. Give the person, number and tense of the verbs percussit and effugerunt.

cotidie dominus servos percussit quod crudelis erat. Tandem duo trepidi servi effugerunt.
a. Servos is the masculine accusative plural of servus, whilst servi is the masculine nominative plural. Servos is accusative because it is the direct object of the verb percussit (for which dominus is the nominative and the subject) as the slaves are the ones being hit. In the second sentence servos becomes servi because it is now the subject of the verb effugerunt - the slaves are the ones fleeing - there is no direct object.
b. Percussit is the 3rd person singular perfect active indicative of percutio, I strikec. Effugerunt is the 3rd person plural perfect active indicative of effugio, I flee