Could means you CAN do it, but you might decide not to.
Should means, that you can do it, and that it is probably good to do it.
Must means that you can do it, and it's very important that you do it.
Hope that helps
25 Haziran 2013
2
1
Hâlâ cevap bulamadın mı?
Sorularını yaz ve ana dil konuşanlar sana yardım etsin!