求助Maple微分问题，请达人指点！！

[ytinghost]

下面是我的要微分的函数：
L := (1/2)*m[0]((x+l[F]*sin(theta[p](t))*w)^2+(y^2+l[F]*sin(theta[p](t))*x^2-l[F]*cos(theta[p](t))*w^2)^2)+(1/2)*I[0]*w^2+(1/2)*m[1]((x-l[11]*sin(theta[1](t))*w*cos(theta[p](t))-l[11]*cos(theta[1](t))*sin(theta[p](t))*w)^2+(x-l[11]*sin(theta[1](t))*w*sin(theta[p](t))+l[11]*cos(theta[1](t))*cos(theta[p](t))*w)^2+l[11]^2*cos(theta[1](t))^2*u^2)+(1/2)*I[1](cos(theta[1](t)))*w^4+(1/2)*m[2]((x-l[1]*sin(theta[1](t))*u*cos(theta[p](t))-l[1]*cos(theta[1](t))*sin(theta[p](t))*w-l[21]*sin(theta[1](t)+theta[2](t))*(u+w)*cos(theta[p](t))-l[21]*cos(theta[1](t)+theta[2](t))*sin(theta[p](t))*w)^2+(x-l[1]*sin(theta[1](t))*u*sin(theta[p](t))+l[1]*cos(theta[1](t))*cos(theta[p](t))*w-l[21]*sin(theta[1](t)+theta[2](t))*(u+v)*sin(theta[p](t))+l[21]*cos(theta[1](t)+theta[2](t))*cos(theta[p](t))*w)^2+(l[1]*cos(theta[1](t))*u+l[21]*cos(theta[1](t)+theta[2](t))*(u+v))^2)+(1/2)*I[2](cos(theta[1](t)+theta[2](t)))*w^4-m[0]*gh-m[1]*g(h+l[11]*sin(theta[1](t)))-m[2]*g(h+l[1]*sin(theta[1](t))+l[21]*sin(theta[1](t)+theta[2](t)))

利用Diff微分：ll := diff(L, x)，结果如下：

(1/2)*(D(m[0]))((x+l[F]*sin(theta[p](t))*w)^2+(l[F]*sin(theta[p](t))*x^2+y^2-l[F]*cos(theta[p](t))*w^2)^2)*(2*x+2*l[F]*sin(theta[p](t))*w+(4*(l[F]*sin(theta[p](t))*x^2+y^2-l[F]*cos(theta[p](t))*w^2))*l[F]*sin(theta[p](t))*x)+(1/2)*(D(m[1]))((x-l[11]*sin(theta[1](t))*w*cos(theta[p](t))-l[11]*cos(theta[1](t))*sin(theta[p](t))*w)^2+(x-l[11]*sin(theta[1](t))*w*sin(theta[p](t))+l[11]*cos(theta[1](t))*cos(theta[p](t))*w)^2+l[11]^2*cos(theta[1](t))^2*u^2)*(4*x-2*l[11]*sin(theta[1](t))*w*cos(theta[p](t))-2*l[11]*cos(theta[1](t))*sin(theta[p](t))*w-2*l[11]*sin(theta[1](t))*w*sin(theta[p](t))+2*l[11]*cos(theta[1](t))*cos(theta[p](t))*w)+(1/2)*(D(m[2]))((x-l[1]*sin(theta[1](t))*u*cos(theta[p](t))-l[1]*cos(theta[1](t))*sin(theta[p](t))*w-l[21]*sin(theta[1](t)+theta[2](t))*(u+w)*cos(theta[p](t))-l[21]*cos(theta[1](t)+theta[2](t))*sin(theta[p](t))*w)^2+(x-l[1]*sin(theta[1](t))*u*sin(theta[p](t))+l[1]*cos(theta[1](t))*cos(theta[p](t))*w-l[21]*sin(theta[1](t)+theta[2](t))*(u+v)*sin(theta[p](t))+l[21]*cos(theta[1](t)+theta[2](t))*cos(theta[p](t))*w)^2+(l[1]*cos(theta[1](t))*u+l[21]*cos(theta[1](t)+theta[2](t))*(u+v))^2)*(4*x-2*l[1]*sin(theta[1](t))*u*cos(theta[p](t))-2*l[1]*cos(theta[1](t))*sin(theta[p](t))*w-2*l[21]*sin(theta[1](t)+theta[2](t))*(u+w)*cos(theta[p](t))-2*l[21]*cos(theta[1](t)+theta[2](t))*sin(theta[p](t))*w-2*l[1]*sin(theta[1](t))*u*sin(theta[p](t))+2*l[1]*cos(theta[1](t))*cos(theta[p](t))*w-2*l[21]*sin(theta[1](t)+theta[2](t))*(u+v)*sin(theta[p](t))+2*l[21]*cos(theta[1](t)+theta[2](t))*cos(theta[p](t))*w)

请问为什么Maple微分的不彻底，怎样才能改正呀，请达人指点下！！