Who built the first airplanes?
The Wright Brothers
Some planes today use ______.
jet engines
It spins like a fan's blades.
propeller
They can fly in any directions.
helicopters
They are pushed by the wind.
hot-air balloons
They are like long balloons.
blimps
A brother who is related through only one parent instead of two
half brother
One who belongs to a group
member
a brother or sister
sibling
a man who is married to one's daughter or son
son-in-law
children of one's husband or wife from a previous marriage or relationship
stepchildren
a man who has married a child's mother but who is not the child's birth father
stepfather
A bridge over a highway or road
overpass
In building a bridge, a ___ holds the water back.
dam
In a bridge, they are like the legs of a table.
piers
The ____ make the concrete stronger.
steel bars
