These cells form a slick surface that helps the blood move without friction.

这些细胞形成光滑的表面，帮助血液无摩擦地流动。

Again, this is a very slick surface.

同样，这是一个非常光滑的表面。

But, watch out for slick surfaces.

但是，请注意光滑的表面。

The innermost tunic is called the tunica intima, which includes the endothelial cells, which create a slick surface that minimizes friction for blood moving through it.

最内层者称为内膜，有内皮细胞构成；它们形成了光滑表面，使血液流经时的摩擦降到最低。

The symmetrical shape is for equality, the slick surface for peace, and the undulating water motif in its lower body for the River Seine in Paris.

对称的形状象征着平等，光滑的表面象征着和平，下半身起伏的水面象征着巴黎的塞纳河。