Modals are different from normal verbs: 1: They don't use an 's' for the third person singular. 2: They make questions by inversion ('she can go' becomes 'can she go?'). 3: They are followed directly by the infinitive of another verb (without 'to'). 4: They don’t express any meaning by themselves

CAN Ability Most people can do something to protect the environment. Request Can I join your group? Suggestion Teachers can encourage students to ride bikes to school. Possibility I can lend you my new electric car.

be able to Ability, Possibility I was able to install solar panels on the roof. Inability The mayor can't solve our pollution problem. Prohibition You can't throw plastic in this bin. can't

could Past ability She could run very fast when she was a child. Polite request Could you water my plants, please? Polite suggestion You could choose organic food next time. Possibility The weather forecast could be wrong.

May Possibility Peter may/might join Greenpeace Polite request May I leave these plastic bottles here, please? Might

Should Ought to advice, opinion We should / ought to keep the sea clean.

need to Necessiity I need to find out what the weather will be like tomorrow. Lack of obligation You needn’t wash the vegetables. They’re clean. Neednt to

Have to obligation, necessity (from a third person). We have to avoid using plastic products. lack of obligation necessity You don't have to worry about swimming here. This river is not polluted. Don’t

must Obligation, strong necessity We must reduce carbon emissions to slow down climate change. Deduction Sam must feel terrible after seeing all that plastic in the river. Prohibition You mustn't waste water. mustn't

Will Formal request Will you open the window, please? Shall offer, suggestion Shall I help you with your environmental research?