Answer:
1. Evan can't build the model because he hasn't been understanding the instructions. - incorrect
2. I've written two poems this month. They are short but it was a lot of work. - correct
3. Francine has been looking online for a rare comic book that is missing in her collection, but she can't find it anywhere. - correct
4. These hiking shoes smell terrible! It's because I've been walking in the woods all week and wearing them every day. - correct
5. Ok, everyone, the dance class has been finishing. Thank you for coming today. - incorrect
6. Grandpa has been cooking in the kitchen all day. I don't know what it is, but it smells delicious. - correct
7. I've only been talking to my ski instructor twice, but I really like him. I think we're going to be friends. - incorrect
8. Angela has painted her bedroom again. It's now all black and white. It looks great. - correct
Step-by-step explanation:
The present perfect simple and the present perfect continuous are tenses we use when we want to talk about past actions or states that are still connected to the present.
The present perfect simple tells us that an action expressed by the verb is still going on or has recently stopped and that it still has an influence on the present. It's built like this: have/has + past participle.
The present perfect continuous tells us that an action started in the past and that it's still continuing in the present. It's built like this: has/have + been + present participle.
You can see more about how these tenses are used in the images below: