concave GRE

1.A concave mirror would project a real inverted image of the silverpoint onto the panel, which van Eyck would trace.

把颠倒实像投射到木板上，于是范艾克便可以在板子上描画。

2.As a practical example, an astigmation corrected scanning flat holographio concave grating (SFHCG) is designed and some results of the numerical and optical experiments are given.

给出一消像散SFHCG设计实例和用这块光栅所做实验结果。

3.Utricles convex abaxially, plane or slightly concave adaxially; rostra 1/8-1/5 length of kernel; seed adherent to pericarp; leaves and bracts acute but not acicular at apex.

胞果凸背，正或者稍；喙1/8-1/5段珠心；种子附着于果皮；叶和苞片锐尖但不是针状在先端。

4.In contrast to prominent ear with underdeveloped antihelix fold, over-convex-antihelix ear reveals a sharp acute angle of antihelix and over-concaved scapha.

摘要相对于“朝风耳”对耳轮过度坦且外翻，对耳轮过度前凸则是厉害对耳轮前凸及舟状部内陷。