Incorrect: The boy who works hard he will win.
Correct: The boy who works hard will win.

Explanation

Incorrect: Each of these girls sing well.
Correct: Each of these girls sings well.
Incorrect: None of my student attended the class today.
Correct: None of my students attended the class today.
Incorrect: One of my servant has gone on leave.
Correct: One of my servants has gone on leave.
Incorrect: Some of my servants has gone on leave.
Correct: Some of my servants have gone on leave.

The present perfect continuous tense is used to talk about an action that started in the past, has continued up to the present and is still continuing.
Structure: Subject + has/have + been + -ing form of the verb + object/complement/adverbials etc.

Incorrect: He is ill since last week.
Correct: He has been ill since last week.
Incorrect: He has been working since two hours.
Correct: He has been working for two hours.
Incorrect: I have not played cricket since a long time.
Correct: I have not played cricket for a long time.

Incorrect: He has stole my pen.
Correct: He has stolen my pen.
Incorrect: John has often beat me at tennis.
Correct: John has often beaten me at tennis.

Incorrect: He told her that he will come.
Correct: He told her that he would come.

Elder and older, Eldest and oldest

Elder is used to talk about people. Older can be used to talk about both people and things. Elder is usually used in speaking of members of the same family. Older is not used with this meaning.