t$_{i}$ = i, i = 1 , 2 , ... has been investigated in [9]. So, Corollary 2 is a generalization of Theorem 4 in [9]. Moreover, in [9], a difference equation is a main tool for the proofs. Similarly, in the other works such as [4, 5, 6, 7, 10, 11, 18, 19] the relation between difference equa- tions and differential equations with piecewise constant arguments are underlined. Here, because of the existence of continuous argument, we have diffuculty to obtain related difference equation. So, we apply another technique which is worked for delay differential equations. Theorem 3. If one of the following conditions is satisfied then every solution of equation (1)-(2) is oscillatory: where l = min { τ, 1 } . Proof. Let conditions (21) or (22) is satisfied. We shall prove that the existence of eventually positive (or negative) solutions leads to a contradiction. Let x ( t ) be an eventually positive solution of equation (1)-(2). Then y ( t ) = ∏ T <t$_{j}$ ≤ t (1 − b$_{j}$ ) x ( t ) is an eventually positive solution of equation (5) such that y ( t ) > 0 , y ( t − τ ) > 0 , y ([ t − 1]) > 0 for n + 1 > t ≥ n > T. Using the same arguments in the proof of Theorem 2, we obtained that z ( t ) defined in (12) is nonincreasing for t > T. We consider two cases: Case 1. τ > 1 . Dividing inequality (14) by z ( t ) , and then integrating from t − 1 12 lim t $_{→∞}$inf t ∫ t − l   ∏ s − τ<t$_{j}$ ≤ s (1 − b$_{j}$ $_{)}$  b ( s $_{) exp}$  s ∫ s − τ a ( u ) $_{du}$  ds > 1 e , (21) lim n $_{→∞}$inf n +1 ∫ n +1 − l   ∏ n − 1 <t$_{j}$ ≤ s (1 − b$_{j}$ $_{)}$  c ( s $_{) exp}$  s ∫ n − 1 a ( u ) $_{du}$  ds > 1 e , (22)