A.  $\stackrel{\to }{AD} = \stackrel{\to }{u} + \stackrel{\to }{v}$

B.  $\stackrel{\to }{EF} = -\frac{1}{2}\stackrel{\to }{u} - \frac{1}{2}\stackrel{\to }{v}$

C.  $\stackrel{\to }{BC} = -\frac{1}{2}\stackrel{\to }{u} - \frac{1}{2}\stackrel{\to }{v}$

D.  $\stackrel{\to }{BC} = \frac{1}{2}\stackrel{\to }{u} + \frac{1}{2}\stackrel{\to }{v}$