BUYING AND SELLING:

• Compound sentence: I want to buy a new laptop, but I don't have enough money.
• Complex sentence: After I finish my work, I will go to the mall to buy some clothes.
• Compound-complex sentence: She went to the store to buy some groceries, but she forgot her wallet, so she had to go back home to get it.

SPORTS:

• Compound sentence: I like playing basketball, and my brother likes playing soccer.
• Complex sentence: When I was young, I used to play tennis every weekend with my dad.
• Compound-complex sentence: I enjoy swimming in the morning, but I also like going for a run in the evening when it's cooler.

FRIENDS AND RELATIONS:

• Compound sentence: My sister is studying abroad, so we keep in touch through video calls, and we send each other messages every day.
• Complex sentence: Although we haven't seen each other in years, we still keep in touch and talk on the phone regularly.
• Compound-complex sentence: My best friend and I have known each other since we were kids, and we still hang out all the time, even though we live in different cities now. However, we always make sure to plan trips together every year.