Engine is to car as heart is to ...
human
Water is to river as sand is to ...
desert (or beach)
Honey is to bee as milk is to ...
cow
Roots are to plants as foundation is to ...
building
Tree is to forest as star is to ...
galaxy (or space)
Pen is to writing as paintbrush is to ...
painting
Glasses are to eyes as headphones are to ...
ears
Battery is to remote control as charger is to ...
smartphone
Sail is to sailboat as wing is to ...
airplane
Tires are to car as shoes are to ...
feet
Key is to lock as password is to ...
computer
Chef is to kitchen as conductor is to ...
orchestra
Fuel is to fire as oxygen is to ...
life
Feather is to bird as fur is to ...
mammal
Gasoline is to car as food is to ...
human
Pencil is to eraser as knife is to ...
cutting board
Glove is to hand as sock is to ...
foot
Moon is to night as sun is to ...
day
Heart is to love as brain is to ...
think
Wheel is to bicycle as oar is to ...
rowboat
Petal is to flower as leaf is to ...
tree
Sun is to solar system as nucleus is to ...
atom
Umbrella is to rain as sunscreen is to ...
sun
Keyboard is to computer as steering wheel is to ...
car