I need help on this, please tell me what it is.

Acompound machine is also called a machine. a. force b. simple c. complex d. directional

Which two particles are found in the center of an atom

Which is not true of the intertropical convergence zone? a) it features heavy precipitation b) it's where the trade winds collidec) it's a high-pressure zone with sinking air d) it is also known as the doldrums