Answer:
- knew
- started
- has not been
- told
- has decided/decided
- have planned
- have learned
- started
- did not know
- became
Step-by-step explanation:
Past simple vs. Present perfect
- The past simple tense is the basic form of the past tense of a verb. This is when -ed is added to the end of a verb to make it appear in the past tense.
- The present perfect tense is used for events in the past that have present consequences. It can also be used to describe events in the recent past. The present tense of "has" is typically used with the past participle of a verb.
- The tenses can usually be used interchangeably.
- I knew/have known him (past simple/present perfect)
- Since I started working here in 2014. (past simple)
- Recently, he has not been very well. (present perfect)
- A few days ago he told me news that I wasn't expecting. (past simple)
- He decided/has decided to retire. (past simple/present perfect)
- For the past two years, Jack and I have planned a number of courses. (present perfect)
- I have learned a lot from him. (present perfect)
- When we first started working together. (past simple)
- I did not know much about teaching to be honest. (past simple)
- I became a better teacher because of him. (past simple)
Please let me know if this helped!!!