the correct use of " with" and " have"

I am still confused on the usage of " with" and " have ". I need help as to see whether the following sentences are fine with "with" and " have ".

1. I have worked in five companies before I joined ACK Company. Is it correct to use " have" in this sentence ? Can I write : I worked in five companies before I joined ACK Company .

2. Currently, I'm involved with the writing of modules and training of in-service trainers as part of their continuing professional development.

As for sentence 2, can I use " in " instead of using " with" ( I'm involved with writing ).

Thank you.

Originally Posted by Keen to know

I am still confused on the usage of " with" and " have ". I need help as to see whether the following sentences are fine with "with" and " have ".
1. I have worked in five companies before I joined ACK Company. Is it correct to use " have" in this sentence ? Can I write : I worked in five companies before I joined ACK Company .
2. Currently, I'm involved with the writing of modules and training of in-service trainers as part of their continuing professional development.
As for sentence 2, can I use " in " instead of using " with" ( I'm involved with writing ).
Thank you.

1. In the first sentence you should use past perfect tense because the action is prior to that in the second sentence:

I had worked in five companies before I joined...

2. Currently, I am involved in writing some modules and [in] training in-service trainees as part of....


Regards,