Hello Katya. Thank you for doing your homework. Sentence No 1: correct. No 2: write 'in a row' instead of 'straight'. No 3: "had been late" instead of "missed". Sentence number 5: 'because' instead of 'because'. No 6. 'He was walking' instead of 'was went' (such a construction does not exist). No 7: 'Had not gone' instead of 'had not went' (such a construction does not exist). Sentence No 8: 'understand' is not used in continuous tenses. You should say "he understood nothing".