You forgot to check these other sentences. I really hope you can go through them, too!

1)Can you check the following sentences for me, please?
Can you please tell me a synonym for the words in parentheses?
Thank you.

1)Alonso is shipwrecked near an enchanted island with his son and the Duke of Milan.
2) The tempest was raised (synonym? caused, provoked)by Prospero, a magician who lives on the island with his daughter Miranda.
3) Prospero confesses (Miranda?) that he was the rightful (synonym, legal?) duke of Milan. Howeverm, as he was more interested in the study of magic than in the affairs of the state, his brother deposed him setting him adrift (synonym) on a small boat together with his three-year-old daughter Miranda.
4) They were stranded on an enchanted island, where the witch Sykorax had once taken (found?) refuge. The island was now inhabited by Sykorax's son (?), Caliban, a strange creature of brute intelligence and Ariel, the spirit of air. Ariel had been kept prisoner in the trunk of a tree by Sykorax and was eventually released (freed, liberated?) by Antony.
6)Alonso is desperate (?) because he thinks his son drowned or had drowned??

Franco... use this site for synomyms!

Put in your favorites... it is invaluable!

http://thesaurus.reference.com/

Sure, I'd be happy to check these sentences for you!

1) Alonso is shipwrecked near an enchanted island with his son and the Duke of Milan.
- This sentence appears to be grammatically correct and coherent. No revisions are needed.

2) The tempest was raised (synonym? caused, provoked) by Prospero, a magician who lives on the island with his daughter Miranda.
- The word "raised" can be replaced with "caused" or "provoked" to convey a similar meaning. Both synonyms work in this context.

3) Prospero confesses (Miranda?) that he was the rightful (synonym, legal?) duke of Milan. However, as he was more interested in the study of magic than in the affairs of the state, his brother deposed him, setting him adrift (synonym) on a small boat together with his three-year-old daughter Miranda.
- The word "confesses" can be replaced with "tells" if you prefer a simpler synonym. Regarding the word "rightful," a possible synonym would be "legal." Lastly, "adrift" can be replaced with "floating" or "castaway" to maintain the meaning in this context.

4) They were stranded on an enchanted island, where the witch Sykorax had once taken (found?) refuge. The island was now inhabited by Sykorax's son (?), Caliban, a strange creature of brute intelligence, and Ariel, the spirit of air. Ariel had been kept prisoner in the trunk of a tree by Sykorax and was eventually released (freed, liberated?) by Antony.
- The word "taken" can be replaced with "found," as you suggested, to express the same idea. As for Sykorax's son, I'm not sure if there is a specific name given in the text, so it remains uncertain. Lastly, "released" can be replaced with either "freed" or "liberated" to maintain the meaning in this context.

6) Alonso is desperate (?) because he thinks his son drowned or had drowned??
- In this case, the word "drowned" is appropriate to describe Alonso's fear for his son. It implies the possibility that the son is dead due to drowning.

Please note that my answers are based solely on the information provided in the sentences you presented.