My cousin ,that is a research chemist, works in the food industry.
find the mistake

My cousin, who is a research chemist, works in the food industry

research.....................................

who=that or not

chemist researcher

thaaaaaaaaaaaaaaaaaaaaaaaaaaaanks
who

who=that or not
من الاخر كتاب المدرسة يقول لا تستخدم that مع
non defining relative clause
يعن لما تشوف كلام بين 2 commas لا تستخدم that
ما تنساش تدعيلى.

who

لما يكون فى commas لاتستخدم that

Thanks a lot