Verb conjugation of "filter" in English

Regarding the meeting in early May: I could not reschedule the appointment at my daughter's doctor and I will definitely know if I can come during the first 2 weeks. I guess we should talk next week.
Please explain me the exact differences between British and American .... This year I'm trying to make the TOEFL. We can then discuss how we can prepare for this exam. I failed the first time.
What problems did you have when you had to share your flat with your mates? Probably you were not used to it. We say that when we live close we usually discover many issues that were not known.