Well, If you're going to write these sentences down then you need to put a comma. But if you are going to use it in a conversation, those are perfectly fine.

In this scenario, gig means JOB. The word gig is commonly used by musicians. When a musician says, "I have a gig tomorrow", it means he has a job tomorrow.

For me, "I'm interested in this part of the book", is a correct sentence. The preposition "in" is often used in idiomatic expressions or stereotyped expressions, so that familiarity with these expressions will help in the choice of the correct preposition. According to Oxford Dictionary: "There’s no necessity to ban prepositions from the end of sentences. Ending a sentence with a preposition is a perfectly natural part of the structure of modern English" http://oxforddictionaries.com/words/ending-sentences-with-prepositions

Jack:My brother has no hat for himself. - My brother doesn't own any hat. Jim:oh,but I saw him wearing a nice hat yesterday,whose____(A:was B: is) it? B Jack:It must______(A:have been B:be) mine. B Jim:______(A:was B:is) your new hat? -- Was it your new hat? Jack:Well,it can't____B______(A:have been B:be) my new one.My new hat is in my room right now,so is must___B___(A:have been B:be) my old one. Well...I can see the difference between "He can't have been reading."and "He can't be reading now." ,but such as "She can't have been Japanese,she must have been Chinese" really troubles me.Why not just say "She can't be Japanese,she must be Chinese." -- You're correct. Besides, the first sentence doesn't make any sense. A:Did we ever meet a Japanese girl at the yeaterday party? -- Did we meet a Japanese girl at the party yesterday? B:That girl wearing yellow dress may have been Japanese.(Why not just say:"That girl wearing yellow dress may be Japanese.") -- That girl wearing a yellow dress looks like a Japanese. C:And the one who weared a strange black shirt_____(A:was B:is) Japanese. -- And the one who's wearing a strange black shirt is a Japanese. another: A:Sir,I am afraid the one who killed your brother is......you know..maybe Jack. -- Sir, I'm afraid that the one who killed your brother is... you know... maybe Jack. B:No! The murderer can't___B___(A:have been B:be C:both is ok) Jack! He can't be! Jack is my best friend! How ____(A:was B:is) Jack the murderer? - How did Jack became the murderer? I am not sure if the last sentence I wrote makes sence or have any grammatical problem.please help me get it right，thanks!!! Thanks for coming here! All the sentences here were written by me.If any of them sounds strange or just doesn't really make sence,point it out please^ ^

For Question #1: Well, it means you are not a teacher anymore. However, the sentence is not complete nor clear. If I am not a teacher anymore, I would rather say, "I was a teacher before." For Question #2: Yes, you're still a teacher.

This quote is about things and small things. Every person has his or her own desire to accomplish big things in life. But it is our great responsibility to succeed in small things and treat it like these are great and noble.

"Tooty" is a name that is given to a pet or something. It may be a puppy, kitten... etc