English grammar worksheet focusing on using articles "a," "an," and "the" correctly in sentences.

To solve this problem, we need to fill in the blanks with the correct articles: a, an, or the. Here's a step-by-step explanation for each sentence:

Rules for Articles:

1. "a" is used before words that start with a consonant sound.
2. "an" is used before words that start with a vowel sound.
3. "the" is used when referring to something specific or unique.

Solution:

#### a) ______ elephant is a mammal.
- "Elephant" starts with a vowel sound, so we use "an".
- Answer: An elephant is a mammal.

#### b) We saw ______ magnificent polar bear.
- "Magnificent" starts with a consonant sound, so we use "a".
- Answer: We saw a magnificent polar bear.

#### c) Eating ______ apple can help keep you healthy.
- "Apple" starts with a consonant sound, so we use "an".
- Answer: Eating an apple can help keep you healthy.

#### d) When ______ dog ran, it was tired.
- Here, we are referring to a specific dog (implied by the context), so we use "the".
- Answer: When the dog ran, it was tired.

#### e) Yesterday, I bought ______ blue dress.
- "Blue" starts with a consonant sound, so we use "a".
- Answer: Yesterday, I bought a blue dress.

#### f) Eating ______ banana can keep you healthy.
- "Banana" starts with a consonant sound, so we use "a".
- Answer: Eating a banana can keep you healthy.

#### g) ______ moon orbits the earth once every twenty-seven days.
- The moon is a unique object, so we use "the".
- Answer: The moon orbits the earth once every twenty-seven days.

#### h) Melissa has ______ new dog as a pet.
- "New" starts with a consonant sound, so we use "a".
- Answer: Melissa has a new dog as a pet.

#### i) ______ music is playing on the radio.
- "Music" is a general term here, and we use "the" because it refers to the music currently playing.
- Answer: The music is playing on the radio.

#### j) Please give me ______ kilogram of rice.
- "Kilogram" starts with a consonant sound, so we use "a".
- Answer: Please give me a kilogram of rice.

Final Answers:

1. An elephant is a mammal.
2. We saw a magnificent polar bear.
3. Eating an apple can help keep you healthy.
4. When the dog ran, it was tired.
5. Yesterday, I bought a blue dress.
6. Eating a banana can keep you healthy.
7. The moon orbits the earth once every twenty-seven days.
8. Melissa has a new dog as a pet.
9. The music is playing on the radio.
10. Please give me a kilogram of rice.

Final Answer Box:
\[
\boxed{
\text{An, a, an, the, a, a, the, a, the, a}
}
\]