Under which two conditions can such an underground water
supply form? Note the correct answers.
A with an impervious layer in the subsurface with a porous
layer beneath it
B with sufficient precipitation
C with a porous layer in the substrate with a second porous
layer underneath
D with a porous layer in the substrate with an impermeable
layer beneath it
E with sufficient useful precipitation now or in the past.
F with an impermeable layer in the subsurface with a
second impervious layer beneath it