It depends on what you are looking for. If you want to improve your conversational English, you should watch more comedies and sitcoms centered around a group or family, like FRIENDS, Modern Family, New Girl, etc. If you just want to enjoy the movies and shows, I would watch what genre you like the most, for example, I like thrillers and dramas.

The sentence is a run-on and too long. Correction: "In addition, the stress difference before retracting mandrel and after is calculated and becomes larger with the increase of the core number. Thus, the reduction extent of springback angle in Table 1 increases with the number of cores."

The other answers are spot on, but the phrase was used in Community, a comedy on NBC. #justosyouknow haha

I think the best way to learn is to have an English partner and use him/her for practice. Have them say complex questions and tell them what they mean't. Also, improving your vocabulary as well as familiarity with how the language flows and sounds like will improve your listening score.

I think this is a grammatically correct, but complex sentence. It is better to split it into two sentences and word it better.

The first question seems a little confusing, but I am pretty sure the answer is a) He was surprised by the recommendation. The second question's answer is c) upgrade.