I am writing a story, and suddenly I have a problem that is driving me mad. When I finish a sentence after a few words on one line, and drop down to thee next line, it automatically spreads the previous line out to fill the width. It hasn't done this for the other dozens of pages before. Here's an example:

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“Yes” I said, holding up a French DVD. “Like this but English speaking ones”
“Ah Eenglish”. Then he looked suspiciously in both directions, and pulled out a cardboard box from under the table. It was full of new and recent cinema releases. I had watched other customers further up the road, and saw that the going rate seemed to be about 70 dirhams (£5) so I picked three, and got ready to barter with him. “How much for these?” I asked.


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But when I drop the last sentence down, this happens:

so I picked three, and got ready to barter with him.
“How much for these?” I asked.

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How can I stop this happening and get on with the rest of the story ????