Answer:
Sure, I can help you with that. Here are the rewritten sentences:
a. The girl has **beautiful eyes**. (nothing)
b. He has been writing a book **for 5 months**. (for)
c. Rabindranath Tagore died **in 1941**. (in)
d. **Is it** hot today? (is it)
**Although** it rained a lot, we walked out. (although)
2.
a. Rohan said that his bike wasn't starting.
b. You are served by waiters at the restaurant.
c. What is the name of the place where drinking water is not available?
3.
a. She goes to the temple every Saturday.
b. The principal and writer are going to say something about the book.
I hope that helps! Let me know if you have any other questions.