9-23. push, pushes, to push, pushing, pushed.

[You push X.] = You are on one side of X. There is a place near the other side of X where X can move. Touching this one side of X, you move towards the place on the other side, and this causes X to move towards this place.

[It was difficult to push the big machine into the building.]

9-24. atom, atoms.

[X is an atom.] = X is something very small. You cannot see one of these, but you can see groups containing very many of these, because they are all the parts of all things you can see and touch. There are less than one hundred kinds of these very small things existing inside all the parts of the things people often use.

[Water contains two kinds of atoms.]

9-25. chemical, chemicals.

[X is a chemical.] = X is a kind of solid or liquid or gas. Each very small part of X is like this: Each contains the same number and kinds of connected atoms.

[Mixing these two chemicals causes them to become hot and change colour.]

[An animal will die if it drinks this kind of chemical.]

9-26. sweet.

[X is sweet.] = X is something people can taste, and most people think it tastes good. Light causes many kinds of green plants to make a chemical. When much of this chemical moves into the fruit, it makes the fruit have a taste that most people enjoy eating. X tastes like this chemical.

[I want something sweet to drink.]

Tony enjoys eating this __________.

• because it contains many atoms
• because it is sweet
• because it moves when you push it