To use the irregular verb "ser" (which means "to be") in the present tense, we need to remember its different forms.

Unlike regular verbs that end in -ar, -er, or -ir, which have set patterns, "ser" is special. Here’s how to conjugate "ser" for each subject pronoun:

• Yo soy (I am)
• Tú eres (You are)
• Él/Ella/Usted es (He/She/You (formal) is)
• Nosotros/as somos (We are)
• Vosotros/as sois (You all are - informal in Spain)
• Ellos/Ellas/Ustedes son (They/You all are)

Now that we know the conjugations, let's see how to build simple sentences with "ser."

The sentence structure to remember is: subject + verb + object. Here are some examples:

• Yo soy estudiante. (I am a student.)
• Ella es profesora. (She is a teacher.)

When we ask questions in Spanish, we use question words. Here are a few examples:

• ¿Quién es él? (Who is he?)
• ¿Qué es esto? (What is this?)

It's also important to use definite (el, la) and indefinite articles (un, una) the right way. For example, in the sentence "El libro es interesante." (The book is interesting), "el" (the) refers to a specific book.

When we use adjectives, they need to match the nouns they describe in both gender and number. Here’s how that works:

• El libro es rojo. (The book is red.)—masculine singular
• Las casas son rojas. (The houses are red.)—feminine plural

Negation is another important part of Spanish. To say something is not true, just put “no” in front of the verb. For example, “No soy profesor.” (I am not a teacher.)

By practicing these rules, you'll get better at using "ser" and other present tense verbs in Spanish!