由参数方程 ^2)=() .-|||-A -dfrac (1)(2)(e)^-4t+dfrac (3)(4)(e)^-5t-|||-B -dfrac (1)(2)(e)^-4t-dfrac (3)(4)(e)^-5t-|||-C -dfrac (1)(2)(e)^4t-dfrac (3)(4)(e)^5t-|||-D -dfrac (1)(2)(e)^-4t+dfrac (3)(4)(e)^5t