Alternative characterization of concave and convex functions which is sometimes useful . 对于凹函数和凸函数还有一个替补的表征，有时它是有用的。
The depression of the ground are covered with black and fertile soil, where the vegetation is vigorous . 凹地上覆盖着一层肥沃的黑土，植物长得茂盛。
Pressures under the margin of a deep cavity would similarly cause the underlying material to flow into it . 在一个深凹形体边缘的压力，同样会导致边缘部分物质的流入。
The mass of gas in the depression will increase, and because of its weight the hollow will sag even more . 洼地中的气体质量会增加，并且由于它的加重，凹地将更加陷下去。
His hair had grown very gray in but a few weeks, his step slow, his face pallid, his eyes sunken . 只在几星期内，他的头发白了许多，他的脚步迟钝，他的面色苍白，眼情凹了下去。
From the exterior, many of the mobile homes showed some dents in walls or roofs and a certain amount of distortion . 从外部来看，许多活动住房的墙壁或房顶有凹痕和相当程度的扭曲。
Copper wires are carried back from the rotating terminals to the individual sliprings along grooves in the outside of the shaft . 铜导线从旋转凸块沿着轴外部的凹糟引回到各个滑环上去。
Encouraging results have also been obtained with the anodic plasma-oxidation technique for nonrecessed oxides . 对于无凹槽氧化物层，采用阳极等离子体氧化技术也已获得了鼓舞人心的结果。
These cracks occurred at either the beam flange or in the column flange depending on the reentrant corner weld angle . 这些裂纹视凹形焊角的不同，或者出现在横梁翼缘上，或者出现在立柱翼缘上。
"they're getting slack, i'm afraid," said the little deep-eyed man, "our principle is to amuse everyone. " “我怕他们都有点不上劲了，”凹眼睛的矮个子说，“我们的原则是要使得人人都有兴趣。”
