1. They started to swim five years ago.

⇒ They have started to swim for five years.

2. Collecting dolls is lan's hobby 

⇒ Lan is hobby in collecting dolls.

3. I find arranging flowers wonderful.

⇒ My body feels great flower arrangements.

4.  My class has thirty four students.

⇒ There are thirty four students in my class.

5. I have some spots 

⇒ I think you should wash your face regularly.

III: 1, They have swum for five years
2, Lan is interested in collecting dolls
3, My hobby is arranging flowers wonderful
4, There are fifty four students in my classs
5, I think I should have some spots