凹形

Leaves arising from rhizome, simple, alternate, floating, emersed, or submersed, long petiolate but short petiolate on submersed vernal ones; leaf blade undivided, usually with a basal sinus, often peltate.

单叶着生于根状茎，互生，漂浮，挺水，或沉水，有长叶柄但是在春季的沉水叶上为短叶柄；叶片不分裂，通常基部有凹缺，通常盾形。

The family is characterized by a primitive protrogomorphous-sciurognathous zygomasseteric structure and pauciserial incisor enamel, but the cheek teeth are precocious in development of hypocone and hypolophid.

共 4属 6种。新科的特征是：始啮型头骨-松鼠型下颌；门齿釉质层散系；颊齿具有发育的次尖和下次脊，后期种类上颊齿的外侧齿尖的唇侧发展成平凹到新月形。

Seeds obpyramidal, tetrahedral, or obovoid, narrowly winged along angles, transversely rugose, squamulose winged, lamellate, or concave reticulate.

种子倒金字塔形，四面体的，或倒卵球形，狭翅沿着棱，横向具皱纹的，具小鳞片具翅，片状，或凹网状的。

Composed of or containing gristle.A small blue butterfly of the family Lycaenidae.

一种翼前有凹痕的蛱蝶科蝴蝶，其后翅的下侧有逗点形斑点。

Leaf base with a broad sinus; flower buds broadly ovate; corolla glabrous; stigma head conical, not exserted from corolla tube; follicles puberulent, muricate, or rugose

叶基部具一宽的凹缺；花芽宽卵形；花冠无毛；圆锥状的柱头头状花序，并非从花冠筒外露；被微柔毛，粗糙的蓇葖果，或具皱纹 2 Metaplexis hemsleyana 华萝

Inflorescence spikelike, cylindrical, composed of spiny or bristly deciduous burrs arranged along an angular, often sinuous rachis; burrs sessile or with an obconical basal stipe, each composed of 1 or more sessile spikelets surrounded by an involucre of spines and bristles; bristles flexuous or more often spinous,± flattened, grooved on the outer face, united below, the degree of union varying from a small basal disk to a deep cupule, inner spines or bristles often ciliate around spikelets. Spikelets lanceolate, acute; glumes unequal, shorter than spikelet, lower sometimes suppressed; lower floret membranous, staminate or neuter; upper floret firmer, protogynous.

花序穗状，圆筒状，由落叶的毛刺沿着一具角安排的具刺的或具刚毛，通常波状的轴组成；毛刺无梗或具基部的倒锥状柄，每一个由1无梗或更多组成以总苞的刺和刚毛包围；或更多的刚毛曲折通常spinous，多少扁平，在外面上具凹槽，下面的合生，协会的度从一小的基部的花盘变化到一深的壳斗，小穗披针形，锐尖；不等长的颖片，短于小穗，降低有时压抑；更低的小花膜质，雄蕊花的或中性；坚定的上面小花，雌蕊先熟。

Receptacle obovoid, truncate and depressed at apex.

花托倒卵球形，截形和下凹的在先端。

Especially, it is found that there exists three types of relative permeability of water such as concave, convex to the water saturation ax and the reversed "S" pattern. The super-low permeability reservoir is sensitive to pressure, apparent with millipore undersaturation and water blocks. In this study, a new concept of irriducible undersaturation is brought up. And a new mode to describle the process of imbibition dynamics is used to reveal and confirm the mechanism of pinhole enveloping macropore as following: pendular ring of wetting phase gathers→it fills throat→it truncates nonwejting phase . The expression of pressure distribution and the equation of oil production are deduced under conditions of non-darcy linear seepage and non-linear seepage.

尤其发现水相相对渗透率曲线存在凹向、凸向含水饱和度轴及反S形三种形式；特低渗透储层的压力敏感性强，微孔隙的欠饱和及水锁效应显著，本文研究中提出欠束缚水饱和度的概念，引用一种描述渗吸动态即湿相液环聚集→充填喉道→截断非湿相的演化过程的新方法，更深刻地揭示和证明了&小孔包围大孔&机理；推导出了非达西线性渗流和非线性渗流条件下的压力分布表达式和油井产量方程。

Petals white becoming purplish, longer than sepals; blade narrowly spatulate, apex retuse; claws well developed.

花瓣白色变得略带紫色，长于萼片；叶片狭匙形，先端微凹；瓣爪发育良好。

Leaves oblong; inflorescence dense, pedicels 2--5 mm; petal apex truncate or retuse; stamens and styles longer than petals

叶长圆形；紧密的花序，花梗2 --5毫米；花瓣先端截形或微凹；雄蕊和比花瓣花柱长 3 G。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。