How many simple machines are there?

1.   ?    3
2.   ?    4
   
3.   ?    9
4.   ?    7

is a wheel a simple machine?

1.   ?    no
2.   ?    no
3.   ?    no
4.   ?    yes

is a pulley a simple machine?

1.   ?    no
2.   ?    no
3.   ?    no
4.   ?    yes

is a screw a simple machine?

1.   ?    no
2.   ?    no
3.   ?    no
4.   ?    yes

is a computer a simple machine?

1.   ?    yes
2.   ?    yes
3.   ?    yes
4.   ?    no