I'd be happy to help you check the use of tenses in these sentences. Here are the corrections: A) I have been learning Spanish for three years now. I started when I was 15 years old. Our history teacher has shown us many places and pictures from her trip to Spain. She has visited many places and tried many dishes! I hope to travel to Spain someday in the future too. B) They had been married for 3 years before they got a divorce in 2017. E) The teacher stopped explaining when he realized the students hadn't paid attention. Soon, he became angry and decided to punish them with a surprise test. G) Mia and her friends are going to watch a movie this Saturday. They haven't decided on a movie yet, but it will probably be a romantic comedy. Mia loves romance and a good dose of laughter. These corrections ensure that the tenses are used consistently and appropriately in each sentence.

I have been learning Spanish for three years now. I had started when I was 15 years old (This means that I am 18 years old now). Our history teacher had showed us so many places through the pictures of her trip to Spain. She has visited so many place and tried a wide variety (we can try to avoid redundancy by using a variety of vocabulary) of dishes. I hope I will travel to Spain someday in the future too! B) The were married for 3 years until they got a divorce in 2017. E) The teacher stopped explaining when he realised that the students weren't paying attention. He then became angry and decided to punish them with a surprise test. G) Mia and her friends are going to watch a movie this Saturday. They haven't decided a movie yet, but it will probably be a romantic comedy. Mia loves romance and a good dose of laughter. I made some corrections on the sentences to improved them and tried to add some comments in brackets. I am not sure why you have the letters B, E, and G. It seems a bit out of place, but I think it must be copied from some exercise. Anyways, I hope you fulfill your dreams of travelling to Spain and learning Spanish.

'I have been learning Spanish' - present perfect because you are still learning Spanish. 'I started when I was 15 years old' - simple past because it [starting to learn Spanish] is now finished. 'Our history teacher has shown us OR showed us . .' 'She has visited so many places and has tried so many dishes' OR 'She visited . . and tried . .' 'They had been married for three years before they got a divorce' - past perfect 'had been' because it happened before the divorce. '. . hadn't been paying attention' OR 'hadn't paid attention' - past perfect because it was happening before he became angry and decided to punish them.