Knowledge Representation

Use modal, temporal, and epistemic logics to express the following:

There will be a time in the future after which it will be common knowledge among scientists that time travel is impossible.
F(G(C_scientists(~◊(time_travel))))
I have always known that I might have to leave town.
H(K_I(◊(□(leave_town))))
(A extra F can be added somewhere after K_I.)
Obama must know that from now on every American will know his name.
□(K_Obama(G(E_Americans(Obama))))
Jamaicans all know that the Windies will have to win.
E_Jamaicans(□(F(win)))
E_Jamaicans(F(□(win)))