Final answer:
Modal verbs express the speaker's attitude or intention, while modal adverbs modify the meaning of a verb.
Step-by-step explanation:
A modal verb is a type of auxiliary verb that expresses the speaker's attitude or intention. It is used to show ability, possibility, necessity, or permission. In the given sentences, the modal verbs are:
- Can you help me with my homework?
- I should study for the test tomorrow.
- Will you go to the party with me?
A modal adverb is an adverb that modifies the meaning of a verb and expresses the speaker's attitude or intention. In the given sentences, the modal adverbs are:
- She always sings beautifully.
- I probably won't be able to come to the meeting.
- They definitely want to go on the trip.