Choose the correct options. Sometimes more than one option is possible

Which style/styles is/are suitable for:

an email apologising to your teacher for not doing something

• informal
• semi-formal
• formal

a thank-you letter to a company for the quality of a service they provided

• informal
• semi-formal
• formal

a letter to express sympathy to your cousin after they failed to achieve something

• informal
• semi-formal
• formal

an email congratulating a friend on an achievement

• informal
• semi-formal
• formal