This a Spanish homework. Please I really need help with this. I would really appreciate if anyone could help me with these. Thank you!

1) Ella se no lo va a dar? Is this sentence Correct? 2) Voy a enviarselo. Is this sentence Correct? 3) Por or Para? Yo pagu tres dlares _el libro 5) write a sentence using the PAST TENSE with the subject YO and the verb with Caminar. 6) Rewrite the sentence using direct and indirect object pronouns. Example: Yo envo la carta-Yo se la envio. Yo estoy leyendo una carta a mis hermanos. 7) write a sentence using the PAST TENSE with the subject ELLA and the verb with ESTUDIAR. 8)Este libro es de ella. Is this sentence Correct? 9)Juan trabaja por Luis. Is this sentence Correct? 10) Rewrite the sentence using direct and indirect object pronouns. Example: Yo envio la carta-Yo se la envio. Marta escribe un libro de historia para sus estudiantes. 13) Julio esta se enviandola. Is this sentence Correct? 14) Ella viaja con mi. Is this sentence Correct? 15) Use POR or PARA in the blank. Marta camina la playa. 16) Yo le lo voy a comprar. Is this sentence Correct? 17) Rewrite the sentence using direct and indirect object pronouns. Example: Yo envio la carta-Yo se la envio. Juana no va a dar el libro a Rosa. 18) Rewrite the sentence using direct and indirect object pronouns. Example: Yo envo la carta-Yo se la envio. Marta envia los libros a Julian. 19) Ella trabaja para Juan. Is this sentence Correct