Male Or females ?

Can these be sexed yet? they are about 3 1/2 weeks old.. First i used CFL's for 2 weeks, now they are under 1000w MH... I think I have some females but not for certain.. Advice please !!!

they look female to me mate congrats 1 of them isn't develop yet but i wouldn't worry about it just flower them if you have to, if iw as you i would veg them for another month to get maximum yield