Fill in the blanks.
(a) The inclined plane is a …………….machine.
(b) The wheel and its ……………. form a simple machine.
(c) The sewing machine is a ……………. machine.
(d) ……………. must be applied to make a machine work.
(a) The inclined plane is a simple machine.
(b) The wheel and its axle form a simple machine.
(c) The sewing machine is a complex machine.
(d) Force must be applied to make a machine work.