Choose the right grammatical form in each gap to complete the text

There are no professions [that|that's|who|who's] are too easy. Every job can be difficult in any case. People [whose|who's|which|who]work with clients should be ready to manage conflicts [whose|which|who|who's]often arise. So, if you're not good at communicating and can't deal with angry people, then customer service manager is not the best job for you. Those [whom|whose|who|that]job is connected with technologies must be real professionals in the area of work which they do. For example, computer programmers have to know specific computer languages and codes. People [whom|whose|who|that]occupy medical positions must be well-qualified, responsible and hard-working. Have you known that surgeons can do some difficult surgeries from 6 to 16 hours?