I have to solve the following exercise from "Grammar and vocabulary for Cambridge advance and proficiency" Pag 51 number 4. Specifically I have to complete a sentence so that it has a similar meaning to the first sentence, using the word given. I have to use from 2 to 8 words.
The original sentence is:
I wouldn't have thought there's much chance of that package being here before Friday.
The word given is doubt
The sentence to be filled is
I ..... here before Friday.
This is my solution:
I doubt the package could be here before Friday
However, the book gives me the following one:
I doubt the package will be here before Friday.
At this point I have one questions:
Is the sentence of mine wrong? why?