What is the world's fastest land animal?
lion
cheetah
zebra
none
Which type of cell protects your body from disease?
nerve cells
red blood cells
white blood cells
platelates
All elements are made up of:
metals
ions
compounds
atoms
who invented aeroplane?
arkemidiz
thomas edison
john kenndy
wright brothers
DC power supply has 0 frequency ?
True
False