Considering a transaction which is 2PL but not serial : Would this example be correct?

sl1(x), r1(x), sl2(y), r2(y), xl2(y), w2(y), xl1(x), w1(x), ul1(x), ul2(y)

The main thing i want to be clear about is that can we use exclusive lock without unlocking the shared lock ? 

Thanks :)