设$\stackrel{\rightharpoonup }{a},\stackrel{\rightharpoonup }{b}$是向量，命题"若$\stackrel{\rightharpoonup }{a}=-\stackrel{\rightharpoonup }{b}$，则$\left|\stackrel{\rightharpoonup }{a}\right|=\left|\stackrel{\rightharpoonup }{b}\right|$"的逆命题是

若 $\stackrel{\rightharpoonup }{a}\ne -\stackrel{\rightharpoonup }{b}$，则 $\left|\stackrel{\rightharpoonup }{a}\right|\ne \left|\stackrel{\rightharpoonup }{b}\right|$ 若 $\stackrel{\rightharpoonup }{a}=-\stackrel{\rightharpoonup }{b}$，则 $\left|\stackrel{\rightharpoonup }{a}\right|\ne \left|\stackrel{\rightharpoonup }{b}\right|$ 若 $\left|\stackrel{\rightharpoonup }{a}\right|\ne \left|\stackrel{\rightharpoonup }{b}\right|$，则 $\stackrel{\rightharpoonup }{a}\ne -\stackrel{\rightharpoonup }{b}$ 若 $\left|\stackrel{\rightharpoonup }{a}\right|=\left|\stackrel{\rightharpoonup }{b}\right|$，则 $\stackrel{\rightharpoonup }{a}=-\stackrel{\rightharpoonup }{b}$