omg............we could say like this. trust me~~~~篮球你会打吗? means i doubt that u cant play basketball, so i ask u like this: i put 篮球 at the beginning to highlight that i am asking 篮球, not 足球 not 网球, it is just 篮球. so we could say like this. if u just want to ask a normal question, i should say: 你会打篮球吗? but if u want to express ur doubt, u could say 篮球你会打吗? no problem.