难以

However, the high cost of the catalyst and the metal contamination of the product remain to be surmounted.

但是，金属催化剂的昂贵价格和重金属的污染一直是工业应用的难以克服的障碍。

Han has doubts about waging someone else's war–and his contentiousness is one more burden for Leia to bear as she struggles to help keep the Rebellion alive.

Han对发起战争仍旧持有怀疑之处——他那爱争论的个性更是Leia难以冲破、不小的负担，她努力的想要打赢这场仗。

It is next to Longgang River, conterminous with Longyuan Park in the north, intersects Funing Bridge in the east, and is adjacent to Longping Road in the southwest, It is acultural-commercial street combined with artwork dealing, shopping, catering business, entertainment, leisure and sightseeing .

龙文化乃华夏民族的"根文化"，石文化乃是人类的"母体文化"，古往今来，二者就难以割舍，石是展示龙文化的最好载体之一。深扎于国人文化灵魂深处的龙与穿越了时空的石在龙岗的相遇将造就一场文化盛宴。

For example, the TTT diagram for a 0.8% C steel is a continuous curve although there is both a pearlite and bainite reaction occurring, but it is difficult to disentangle the reactions sufficiently to study their kinetics.

例如，TTT图中，0.8 ％的碳钢是一个连续的曲线虽然是珠光体和贝氏体反应都发生，但是难以将这两个反应分开而充分研究其各自的动力学。

And then the approach is extended to continuous random variable. The optimal rule of general group decision-making is drawn by the new approach, which turns out to be a generalized weighted majority rule. The weight allocated to a decision-maker should be equal to the information quantity he provides.

鉴于Boltzmann—Shannon熵难以直接用来度量群体决策中信息的变动情况，我们提出了一种对离散随机变量的新的信息度量方法，证明了该信息函数仍然满足等状态时信息量最小这一性质；随后将其推广到了连续随机变量。

However, it is not accurate to calculate the problem of continuum media. The FEM may forecast the failure area of the material reasonably, whilst it is hard to calculate the failure process in brittle media.

有限元法适于预测脆性材料损伤和破坏的区域，但难以直接用于计算和模拟脆性材料及结构发生破坏的整个过程。

The discrete element method and the finite element method have their own advantages and weaknesses. Basically, the DEM was developed for predicting the failure problems accompanying with the transition from continuum to non-continuum media. However, it is not accurate to calculate the problem of continuum media. The FEM may forecast the failure area of the material reasonably, while it is hard to calculate the failure process in brittle media. Therefore it becomes a good choice to combine the two methods to construct a hybrid model.

离散元法和有限元法等数值计算方法各有其优势，同时也都存在不足之处：离散元法适于处理由连续介质向非连续介质转化的破坏问题，但对于连续体计算结果精度不高；有限元法适于预测材料破坏的区域，但难以直接用于计算脆性材料破坏过程，因此将两种方法结合可以形成一种较好的混合模型。

So the steady output power is hard to be gotten without the perfect control circuit and control method.

若没有完善的控制电路和控制方法要获得比较稳定的功率输出是难以达到的。

To resolve the problem of the control system, a new control system structure has been designed.

因此，该控制系统的集成化和智能化不足，并且存在难以扩展的问题。

Artificial neural networks has been widely used in pattern recognition, signal and information processing, adaptive controlment, and many other fields because of its self-organize ability, self-adapt ability, robustness and fault tolerance, and which are coming from its parallel processing structure and distribute information storage. But at the same time, they also bring some problems such as the difficulty of getting optimized topology structure and the great training time-consuming, which restrict its reality use.

人工神经网络的并行处理结构和分布式信息存储带来的自组织性、自适应性、鲁棒性和容错性，使得它们在实际应用中已表现出了强大的生命力，成为当今研究的热点之一，已经广泛的应用于模式识别、信号与信息处理、函数逼近、系统辨识和自适应控制的诸多领域，但同时带来了的最优拓扑结构难以确定，训练耗时巨大的问题，也限制了神经网络在实际中的应用。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。