1) Instead of using a period after the word "worry" , use a coma. It's one sentence. Also, you can leave out the word "to" as it is not necessary. Don't worry, I'll help you get your foot in the door. 2) This is actually two sentences. The first sentence concerns Harry's break-up with Genny. The second, Voldemort getting to Harry. Harry decided to break up with Genny. He was afraid Voldemort could get to him through her. 3) This one can be broken into two sentences as well. It is also "a bit wordy" as my English teacher of a mother used to say. I would have said it as follows:. I wanted to get back at him at any cost. His actions were unforgivable. I'm not sure what you are trying to say in number 4 so I'm not sure where to go with it, sorry. 5) This one can also be reworded to be more effective. He drove to work in his new car. His colleagues commend him on his purchase. It is not gramaticaly correct to refer to a purchase as new. 6) This one is rather harsh. It sounds like you are talking to a sibling. I think it would be much more effective and definitely more polite if it were worded differently. Could you please be quiet, you're disturbing me. I apologise if I seem critical. It is not my intent. My mother was an English teacher and drilled this stuff into my head for 12 years. Thank you for the question, you have made me stop and really think about this subject for the first time in 30 years. I have enjoyed it very much and I hope it was helpful.