Final answer:
Sentences are completed using the Present Perfect tense with the correct usage of 'for' and 'since' to differentiate between periods of time and points in time.
Step-by-step explanation:
Here are the sentences completed using the Present Perfect tense and choosing between 'for' and 'since':
- a) She has lived in London for five years.
- b) Nick has known Tom since he moved to London.
- c) Mrs. Harris has been a teacher for twelve years.
- d) Felix has lived in Paris since 1998.
- e) You have not played the piano for several weeks.
- f) I have not seen Emma since last week.
- g) They have studied English for three months.
- h) Sarah has not spoken to Eva since five days ago.
- i) We have been there for three hours.
- j) He has looked for his keys for a long time.
Remember, use 'for' to talk about a period of time (e.g., five years, several weeks), and use 'since' to talk about a point in time (e.g., 1998, last week).