1. This one is a bit complicated because I'm pretty sure the first sentence should be "I heard Yang Yan..." But even though the first part has been written in present tense, "made an English speech yesterday" is past tense (because the event has already happened). Your response would be directed towards the event (not where they heard about it) and therefore should also be in past tense. I feel like the dialogue is strange already and no native speaker really speaks like this, so I'm not surprised that it's a little confusing. Maybe this will make more sense to you. A: I heard Yang Yan made an English speech at the graduation ceremony yesterday. B: She did, and so did I. 2. "What color fish would you like?" isn't really wrong, but "What color would you like the fish to be?" would be more correct. I hope this helps you a little bit. Feel free to let me know if you need me to elaborate.

1) "Hear" is used with a past meaning there.

'So did I' is referred to 'made': he made a speech too.