Which statement is true concerning the straight$-$line method of depreciation?

$1)$Purchase cost is expensed in the year of acquisition

$2)$ Depreciation is recognized evenly over the estimated useful life of the asset

$3)$ Depreciation is equal to the proceeds received on sale less the amount paid to acquire the asset

$4)$ Annual depreciation expense is highest in the early years and decreases over the life of the asset