The use of "A" and "AN"

1. When we can use "AN"?

1.1. We can use "AN" when the following word begins with a vowel sound

1.2. EXAMPLES:

1.2.1. My father is and architect

1.2.2. An ear

1.2.3. An erase

1.2.4. An underground

1.2.5. An umbrella

2. How to use the Articles a / an

3. When we can use "A"?

3.1. We can use "A" when the following word begins with a consonant sound.

3.2. EXAMPLES:

3.2.1. A special day

3.2.2. He is a doctor

3.2.3. My sister is a lawyer

3.2.4. A color

3.2.5. A table