I don't know any websites for the diplomatic phrases but for the second request a few are: "No, thank you" "I rather... [name suggestion here]" <--- If you have another idea. Instead of using you failed, you could say "Try harder and you you'll [pass this/get this/whatever the situation is] next time!' I hope these few phrases are helpful. Gomen demo they were the only ones I could think of at the time.

If it's a formal situation, like with a boss, someone older than you, or someone you must show respect to and not one between friends and family member, then you don't want to say whatever. The best answer would be #5 Don't worry about it, #2 It doesn't matter, and #4 Never mind.

First sentence: Yes. Second sentence: That's correct, though, that might sound a bit weird to a native English speaker. Third sentence: After passerby and before to put a comma. And you might want to take off with and change it to into. George ran with a wheel cart and caused a passerby, which he bumped into, to fall over it. Fourth sentence: I don't think explorate is a word. Maybe you mean exterminate? Exterminate means to destroy. Fifth sentence: Yes. Sixth sentence: A better word then to would be for. Consuming food is vital for human survival. Seventh sentence: Yes. Eighth sentence: It should be polices'. s' is possessive and instead of apathy you might mean empathy. The polices' empathy, towards the outrageous incident, prompted the citizens of Waterloo to start a protest. Ninth sentence: Yes.

On the second one, a better word for rainy would be "raining". It is raining, today. Other than that, both works.