难点

In mechanical industry, high precise coaxiality test of large mechanical components was considered as a complicated problem, because it was very difficult to find a datum line with high precise in long distance.

大型机械零部件同轴度高精度测量是机械行业的共性技术难题，其技术关键和难点在于建立长跨距的高精度测量基准线。

It is important and difficult for isochronous correlation datum of fluvial facies stratum in exploration and development of petroleum, while high resolving power of sequence stratigraphy based on the datum plane cycle is an additional feasible technical method for it.

河流相地层的等时对比一直是油气勘探开发的重点和难点，而基于基准面旋回的高分辨率层序地层学则为此增添了行之有效的技术手段。

Through measuring density inside and in the position with defect, it was discovered that density of defect in timber has corresponding relation to the pressure signal extracted by probe. Mechanism of the mechanical pressure deterred to measure defect in timber was set up.

压阻式木材内部缺陷类无损检测技术要解决的技术难点是木材密度特征的提取方式，以及对信号的分析消噪和判断等技术手段，分为如下几个方面进行研究。

This text will talk about some new methods about the limit of disjunction function in the boundary and the operation of lead number and definite integral.

分段函数是函数问题中难点，本文就分段函数在分界点的极限，导数、定积分的运算问题探讨一些新方法。

The study of protein denaturation is conductive to reveal the mechanism of living phenomenon.

生物大分子是近年来生命科学的研究热点和难点之一，而对蛋白质变性的研究有助于深刻揭示生命现象的机理。

Dentin bonding is always difficult due to its peculiar structure.

牙本质由于本身具有的结构特点，对它的粘接一直是牙齿粘接研究的难点和热点。

The identity and difference in the expressional patterns between distribution functions of discrete random variables and distribution functions of continuous random variables are elaborated,and the main expressional patterns of distribution functions of continuous random variables are summarized,and the derivability of distribution functions of continuous random variables is discussed.

0引言在概率论中，连续型随机变量分布函数的表达形式及其可导性是一难点。其一，离散型随机变量的分布函数有较明显的性质和统一的表达形式，而连续型随机变量，由于其概率密度函数一般为分段函数，根据其分段区间的差异，表达形式差异较大，不容易总结其规律，本文主要比较连续型随机

How to solving comprehensive problems in descriptive geometry is always a difficult teaching point, because good abilities of graphic thinking and space logical thinking are required for the students.

画法几何综合问题是教学的难点，要求学生具有较强的空间想象能力和空间逻辑思维能力。

Innovatively searches the better clutter restrain method, and tries to solve the difficulties of low speed target detection. The major devotement of this dissertation as follows.

本论文主要研究了动目标检测并在SAR图像上定位技术，寻找性能良好的杂波消除方法是其关键，同时试图解决慢速目标的检测和多运动目标的联合检测这个难点。

The differential calculus of the pluralistic function is both the key and difficult point in higher mathematics.

多元函数微分学是高等数学教学的重点和难点之一。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷