Fill in the blanks in the following sentence to make it grammatically correct.
I decided to ____ the book back to the library because I had ____ it.
I decided to take the book back to the library because I had finished it.
Complete the following task based on the instruction and optional input provided.### Instruction:
Fill in the blanks in the following sentence to make it grammatically correct.

### Input:
I decided to ____ the book back to the library because I had ____ it.

### Output:
I decided to take the book back to the library because I had finished it.