What is more useful when it is broken?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

I look at you, you look at me I raise my right, you raise your left. What am I?

Solve the following series:
AZ, GT, MN, __, YB

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Paul's height is six feet, he's an assistant at a butcher's shop and wears size 9 shoes. What does he weigh?

What's a single-digit number with no value?