All phrases in section 1 are technically valid, but some are worded a bit awkwardly. I will assume you mean to say "unhappy", not "unfriendly", at the end of 1b and 1c. 1a has the meaning of 1d and 1e, because it's speaking a bit figuratively. It not does have the meaning of 1b and 1c, although it appears to. To elaborate, 1b and 1c point to a specific moment in time. 1a uses language to suggest it's pointing to a specific moment in time, but in reality, it is not. In 1a, the "when" is intended to mean "when he knows", which makes it mean something like "if", not "at the time". 2b - I will say this sentence is wrong grammar, because "That we talked" means "The fact that we talked" which is referring to something completed in the past, while "might" refers to potential future, so these two parts of the sentence don't match. 2d - I will say this sentence has a very minor but certain mistake, because "might help for us" is bad grammar - it could be corrected by changing it to "might help us" or "might be of help for/to us". 2e has a different meaning, because "would" means "definitely will", which implies certainty, where as "might" implies uncertainly, ie, "we don't know if it will help, but it might". 2g - I will say "for us for us" should have a comma, as in "for us, for us". But this is debatable. Nobody will disagree that the comma is helpful here, but some people may say your version is still technically permissible. Personally, I'm on the fence about whether or not it's a strict violation of grammatical rules - I'm going to say it probably is, due to how much it looks like a mistaken repetition when not spoken with a pause or written with a comma. 2h has a different meaning because it is talking about only "you" talking to Dean (don't forget to capitalise Dean). While 2a is talking about all of "us" ("we") talking to Dean.

1b,c) "The timeS when ... MAKE ..." 1d) good 1e) "People thinking ..." 2b) "That we talk to him might help" (present subjunctive) 2c) good 2d) replace with "be helpful to us" 2e,f) good 2g) technically correct but horrible style. instead: "It will be helpful for us were we to talk to Dean." 2h) It could be helpful to us were you to talk to Dean." Only 3b has the same meaning as 3a. All of #3 are grammatical.

Wow, you have alot of examples - I'll try to give my reaction: 1a. It makes him unhappy when people think he is unfriendly.(original) GOOD 1b. The time when people think he is unfriendly makes him unfriendly. Change TIME WHEN to TIMES THAT and it would be okay. It's not very natural though. 1c. The time that people think he is unfriendly makes him unfriendly. 1d. That people think he is unfriendly makes him unhappy. OK, 1e. People's thinking he is unfriendly makes him unhappy. OK Query: I want to express the meaning of the 1a.( original ). Do all have the same meaning as the 1a.? Which is/are grammatically correct? 2a. It might help if we talked to Dean.(original) 2b. That we talked to Dean might help. DIFFERENT MEANING FROM ORIGINAL - 'That we talked to Dean' is past tense, not a conditional. 2c. Our talking to Dean might help. OK 2d. For us to talk to Dean might help for us. AWKWARD, and the 'for us' at the end of the sentence makes no sense. 2e. It would be helpful for us to talk to dean. BEST 2f. It would be helpful to us to talk to dean. GOOD, but possible different meaning-specifies who it is helpful to. The original sentence does not specify: it just say it would be helpful in general. 2g. It will be helpful for us for us to talk to dean. GOOD, but not conditional 2h. It could be helpful to us for you to talk to dean. OK Query: Which sentences have the same meaning of the 2a (original) Which is/are grammatically correct? 3a. You will be in trouble before you know it.(original) GOOD 3b. Before you know it, you'll be in trouble. GOOD 3c. You will not be in trouble after you know it. BAD - DOESN'T MAKE SENSE 3d. You will not be in trouble until you know it. GRAMMATICALLY OK, but difficult to understand. Does NOT have same meaning as original. 3e. Your knowing it will make you be in trouble. BAD - doesn't make sense. GOOD TIMING - I've used up all the characters.