Just memorizing of vowels for present time is difficult for me. For example, I always confuse that عرف has vowel [a] - in past, and [i] in present. Do you have any hints to memorize them? I know one rule, that if verb is of type "fataha" (has [a] sound in the middle) and has sounds ع،غ، خ، ح, ه، ء in second and third places, so in present we will have [a].For example :فعل-يفعَلُ، جمع - يَجْمَعُ. So I can find out where will be letter [a]. But we have another possibile sounds, [i] and [u]. Ok, I can memorize 5-10-20 verbs... But hundreds of them... Do you evey time check in dictionary?