When the visitor saw with her own eyes the beach which/that was covered with tons of plastic rubbish which/that was washed up from around the world, a chill went down her spine.

, ta rút gọn mệnh đề quan hệ

1/ dạng chủ động : bằng cách bỏ đại từ quan hệ (who/which/that) , đổi động từ thành nguyên mẫu, rồi thêm "ing", nếu có trợ động từ "be" hay "have/has" thì bỏ đi. ex:   The man who drinks coffee  is my uncle.

-> The man drinking coffee is my uncle.

ex: The man who is drinking coffee  is my uncle.

-> The man drinking coffee  is my uncle.

ex : The man who drank coffee  is my uncle.

-> The man drinking coffee  is my uncle.

ex:  The man who was drinking coffee  is my uncle.

-> The man drinking coffee  is my uncle.

ex : The man who has drunk coffee  is my uncle.

-> The man drinking coffee  is my uncle.

2/ dạng bị động:   bằng cách bỏ đại từ quan hệ (who/which/that) , bỏ "be", giữ lại V3/-ed. 

ex: The person who was offered a scholarship is my friend.

->The person offered a scholarship is my friend.

ex: He is the man who is loved by his friends.

-> He is the man loved by his friends.

chúc bạn học tốt nhé !