2-phenylethylbromide when heated with NaOEt, elimination takes place. No deuterium exchange takes place when the reaction is carried out in C2H5OD solvent. The mechanism will be:

It is a primary bromide. So it will undergo elimination either by E2 or E1cB. Since there is no deuterium exchange in C2H5OD solvent, C−H bond is not broken to form carbanion. Hence, the actual mechanism is E2 only.