25. No. "I call you later" is NOT correct. You can not use it instead of the future tense, "I will call you later". 26. It's the second. It means, "I miss her so (much)". 27. Yes. "Manténgalo así!" 28. It's bad (sorry my friend...) It means, "I am through (to the end) with this relationship". 29. It means, "did you read the article through (to the end)?" -- "leiste... enteramente, hasta el fin, etc." como así 30. "even" here means "para que se vuelva plano"

For 25 it is understandable, but future is much better. Either "I will call you later" or "I'll call you later" are correct. 26: "I miss her so" is fine, but it wouldn't be understood as "I miss her also", it would mean "I miss her so much" or "I miss her a lot." 27. "Hold it like so" is usually used when the speaker is demonstrating how to hold it. You might say "Hold it like so" as you are holding something and want the other person to copy you. 28. "I am through with this relationship" means "I am done with this relationship" or "This relationship is over". It's usually used when breaking up (ending a relationship), often if the speaker is upset. To be "through with" usually means to be finished with or to be done with. It can be used for relationships, meals ("Call me when you are through with dinner"), or many other things 29. Same as above, "through" means to be finished or done. "Did you read the whole article?" is another way to say it. 30. "He had a hard time building the deck completely even." This is a little confusing without reading it in context. It probably means it was difficult to build the deck well or to build it straight. "Even" here means straight, lined up, or flat. I hope that helps!