However, efforts to control them are consistently undermined by the difficulty and expense of identifying mosquitoes-of which there are at least 3,500 species, many of them hard to tell apart.
然而，控制这些蚊虫的努力一直没有进展，关键在于鉴别蚊虫的难度和费用——至少有3,500种不同蚊虫，其中有不少很难加以区别。
However, efforts to control them are consistently undermined by the difficulty and expense of identifying mosquitoes-of which there are at least 3, 500 species, many of them hard to tell apart.
然而，控制这些蚊虫的努力一直没有进展，关键在于鉴别蚊虫的难度和费用——至少有3,500种不同蚊虫，其中有不少很难加以区别。
The de-normalization causes difficulty on data retrieval, analysis, and quality control.
这种不规范将为数据检索、分析和质量控制增加难度。
The same difficulty faces investors who control their positions on the basis of daily market volumes.
那些以当日交易量为指标控制自己头寸的投资者也面临同样的问题。
The difficulty for marketers is creating the right kind of buzz and learning to control it.
难的是那些销售人员要建立正确的商业推销手段，并且学会控制这种商业手段。
The coupling complicates the control and brings difficulty to structure design.
这些耦合使控制问题复杂化，给结构设计带来难度。
It brings difficulty to the directly application of sliding mode control on CTO.
这给滑模控制在CTO的直接应用带来了困难。
The algorithm realizes the pole placement of closed loop systems and overcomes the difficulty of the weighting polynomials choice of the quadratic cost function in general adaptive control.
算法的一个特点是能够配置闭环极点，克服了一般自适应控制二次型性能指标中加权阵选择的困难。
Teams that do not have a requirements change control process must field change requests from all quarters and often have difficulty saying "no."
那些没有需求变更控制流程的团队只好把来自各个角落的变更请求全部公布出来，进而常常难于否决这些请求。
It is a new way to use control configuration software to develop simulation-training system. It can reduce the difficulty of development and increase the speed and quality greatly.
利用瘦客户端的工控软件来开发仿真培训系统，可以大大降低开发的难度和提高开发速度和开发质量。
Another differentiating element is service heterogeneity or variability which determines a difficulty to control and standardise a service outcome (Palmer, 1998).
另一个微分单元是服务的异质性或可变性确定难以控制和标准化的服务结果(帕尔默，1998年)。
The difficulty for analysing basin sedimentation is how to control the horizontal variation of continental strata.
如何控制陆相地层横向不稳定性，是盆地分析的难点。
Using preset or custom characters, set up worlds in which you control the plot, action, and difficulty of the game.
使用预设或自定义字符，成立了世界在你控制的阴谋，动作和难度的游戏。
In the implementation of highway projects, there are many uncertainty factors resulting in greater difficulty in cost control.
公路工程实施过程中存在着许多不确定性因素，使其造价控制难度加大。
The associated problems with this weed include its competitiveness, difficulty of control, and the reduction of quality through genetic contamination of pure lines of rapeseed and the like.
与自生油菜(杂草)相关的问题包括杂草的竞争性、难以控制以及通过对油菜纯系的基因混杂造成油菜品质的下降等等。
In system design, firing system of kiln is a multi-variant coupling non-linear system, which is the difficulty of system control.
在系统设计中，窑炉烧成系统作为一个多变量耦合的非线性系统，是控制的难点。
The key and difficulty of the technique is to control the fused drop's deformation accurately, because it influenced the part forming and precision directly.
熔滴变形情况直接影响零件的成形以及成形精度，所以对熔滴的形态变化进行精确控制是该工艺的关键和难点。
The other risk is the difficulty of adopting low-cost risk control strategy because of multiplying interests body, which put emphasis on coordination.
另外虚拟企业的关系风险因多利益体的原因而难以采用低成本的风险控制策略，更多的是强调协调。
Fast and stable swinging up at the situation of a shot track is the difficulty of swing-up control.
在倒立摆小车轨道较短的条件下实现倒立摆快速稳定的摆起，是摆起控制的难点。
Second, we use Binomial Distribution Function to accomplish the control of difficulty proportion in Adaptive Item Bank System.
第三，采用二项分布函数完成自适应题库系统中难度比例的控制。
The engineering design, geology design, main technique difficulty, operation general situation, well track measurement and control technique of the well are introduced.
介绍了该井工程设计、地质设计、主要技术难点、施工概况、井眼轨迹测量及控制技术等。
It is difficulty to design control schemes to ensure the stability of hybrid systems with random switched time because of the complexity of hybrid systems.
由于混合系统的复杂性，设计出能保证混合系统在任意切换时间下都能稳定的控制是比较困难的。
A very severe nonlinear is presented because flight parameters vary along with the flight condition in the flight of missile which brings much difficulty to the design of control system.
导弹在飞行过程中，其飞行参数随着飞行条件的变化而发生较大变化，呈现严重的非线性，给控制系统的设计带来较大困难。
The manipulator track is the difficulty in the robot control.
机械手的轨迹跟踪是机器人控制系统中的一个难点。
According to present condition, the difficulty of floatation control can be recognized.
基于上述现状，认清了浮选自动控制的难度。
The paper brings forwards the adjusting speed technology to solve the problem of power big and disturb of motor and precision control difficulty.
轧机的电机功率大，干扰严重，其调速精度难以控制，文章提出的数字控制调速技术先进、可靠，解决了上述问题。
The sensorless of induction motor field-oriented control employing stator voltages and currents has difficulty in estimating rotor flux in the low-speed range.
在低速范围内，对无传感器感应电动机进行矢量控制时用定子电压和电流推算转子磁通是比较困难的。
The sensorless of induction motor field-oriented control employing stator voltages and currents has difficulty in estimating rotor flux in the low-speed range.
在低速范围内，对无传感器感应电动机进行矢量控制时用定子电压和电流推算转子磁通是比较困难的。
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