Вкаких случаях ставится there is и it is как их отлечать? например: 1) i bought a puzzle yesterdaythere is/it is) in my bag 2) (there is/it is) nothing special about the party

оборот there is используется для указания места, где что-то находится. there is in my bag.

  it is   исользуется как начала в безличном предложении (там где нет подлежащего)   it is nothing special - нет ничего необычного в это вечеринке.

1 it is 

2 there is

их отличают так trere is используется чтобы указать место 

 

My favorite subject in school is mathematics. it is my favorite because i never have difficulty with it and always get good marks in tests.  i suppose i am lucky to be born with a clear-thinking brain. so ever since young, manipulating numbers and figures came easy to me. the wonderful thing about mathematics is that, besides some formulae, there is nothing else to remember. every step in solving a problem is done logically. other subjects like history and geography require a lot of memory work. remembering dates and other facts is hard work compared with the ease and simplicity of mathematical reasoning.while mathematics is simple to me, some of my friends have great difficulty with it. i do not really understand why. they get stuck with simple problems and often give up. so i help them out when i can. the one advantage i have in being good in mathematics is that i do not have to spend a lot of time on it. homework and tests are a breeze. so i have plenty of time left over to study other subjects. sometimes i feel sorry for my less fortunate classmates who get scolded in class for not completing their mathematics homework. anyhow i have come to realize that human beings can be so different in their abilities while they look similar otherwise. some of us are lucky to be good in some things. others may not be so lucky.

1. father told me not to forget to write a letter.

2. nick said that i might   ride his bike.

3. mary said that the weather was beautiful that day.

4. mr. ford told me i would have much work the following day.

5. jane said that she had lost her keys and she didn’t   know what to do.

6. mrs. hillary told me that she would like to tell me one interesting thing.

7. postman said there were no letters for me that day.

8. teacher wanted to know who was on duty that day.

9. salesgirl said she would recommend me those fresh cakes.

10. taxi driver said that my hotel was not far from there.

11. teacher asked us to stop talking.

12. police officer ordered them not to move.

13. friend asked me to help him.

14. ann asked us not to go there.