The correct answer should be informal.
Informal level of language involves the use of slang words, and <em>cool </em>is a slang word, so this sentence cannot be formal by any means. It is also not general due to a slang word being used. Substandard language would mean that it is not grammatically correct, and this sentence is, so this is also incorrect.
Answer:
34. are
35. will come
35. are coming
36. have been wondering
37. will be taking
38. will have been learning
39. will have discovered
40. will be looking for
41. will have traveled
42. to have improved
43. will have developed
Explanation:
Hope this helped!