Identify the subject of the first sentence.

The subject is "Alemitu," which is a singular female name. The pronoun needed should refer to a singular female.

1. Alemitu is grade two student. She is clever student.

The subject is "The book," which is a singular, non-human object. The pronoun needed should refer to a singular non-human object. 2. The book is interesting. It belongs to me.

The subject is "Martha and Beka," which refers to two people, making it a plural subject. The pronoun needed should refer to a plural group of people. 3. Martha and Beka plant trees. They water them every morning.

The sentence "My name is Gelana" indicates the speaker is Gelana. The pronoun needed should refer to the speaker. 4. My name is Gelana. I like English.

The subject is "You and I," which refers to a group that includes the speaker. The pronoun needed should refer to a plural group including the speaker. 5. You and I are in class. We are talking about pollution.

Here are the complete answers:

1. Alemitu is grade two student. $\boxed{\text{She}}$ is clever student.
2. The book is interesting. $\boxed{\text{It}}$ belongs to me.
3. Martha and Beka plant trees. $\boxed{\text{They}}$ water them every morning.
4. My name is Gelana. $\boxed{\text{I}}$ like English.
5. You and I are in class. $\boxed{\text{We}}$ are talking about pollution.