解:(1) \dfrac {\cos (θ+π)×\sin ^{2}(θ+3π)}{\tan (\theta +4\pi )\times \tan (\pi +\theta )\times \cos ^{3}(-\pi -\theta )}= \dfrac {(-\cos θ)×\sin ^{2}θ}{\tan \theta \times \tan \theta \times (-\cos ^{3}\theta )}=1.(2) \dfrac ...