I drew a picture with a drawing tool. = Not very nice? 0 barely have a look =? I will use words to express some mathematical symbols. Please pay attention to the conversion ~ ~ ~

1? Verification: connect AD 1

Because the cuboid ABCD-a1b1c1d1,AD=AA 1= 1,

So what? The quadrilateral ADD 1A 1 is a square.

So what? AD 1 vertical A 1D

Because the cuboid ABCD-a1b1c1d1.

So AB vertical ADD 1A 1?

Because again? A 1D add 1a 1 on the surface? middle

So AB is perpendicular to a1d.

Because? AB and AD 1 intersect at point a.

So A 1D vertical plane ABD 1

Because D 1B is in face ABD 1.

So D 1E is perpendicular to a1d.