不常

When the waterway of a hydroelectric station is rather long,the expensive structures of surge chamber are usually required.

水电站的引水道较长时，常需设置昂贵和复杂的调压井结构。近一二十年来国内外都在研究不设调压井的问题。

The surgeon general says there is no safe level of secondhand smoke.

外科医生常说，有一种不安全的二手烟

And the solutions of arbitrary time-space elastic force equations of time-space variable system multi-linear vectors all are corresponding constant modulus multi-linear vectors, their time-space moving regular are: only change their directions but do not change their moduluses.

而任何时空可变系多线矢的时空弹性力方程的"解"，都是相应的"常模长多线矢"，它在时空的运动规律是：仅改变方向，不改变"模长"。

I usually take the air on the lawn before I go to bed .

我睡觉之前常在草地上散散步。不适合

One can not rely upon him; he is apt to fly off at a tangent .

人们不能依靠他，他的行为常超出常规。

Normal recesses fromthe posterior subtalar joint may frequently extend into thesinus tarsi and should not be misinterpreted as pathologic conditions.

正常的距下关节隐窝常可以出现在跗骨窦，但不应该认为是病理改变。

When located posteriorly at the MDJ, lesions tended to continue downward along the pontine tegmentum and superior cerebellar peduncle, whereas the corticospinal tract was the structure affected in more anteriorly located lesions.

当病灶位于中脑-间脑结合处的偏后方时，倾向于沿着脑桥背盖部和小脑上脚向下延伸；当病灶向下延伸时，红核常不受累。

When located posteriorly at the MDJ, lesions tendedto continue downward along the pontine tegmentum and superiorcerebellar peduncle, whereas the corticospinal tract was thestructure affected in more anteriorly located lesions.

当病灶位于中脑-间脑结合处的偏后方时，倾向于沿着脑桥背盖部和小脑上脚向下延伸；当病灶向下延伸时，红核常不受累。

Three kinds of embryos' chromosome, including goat fertilization embryo, goat-goat cloned embryo and goat-rabbit cloned embryo were analyzed, The results showed that all of them have 60 chromosomes with same character, all were telocentric chromosome, besides the X-chromosome is the second larger telocentric chromosome.

经对超排获得的山羊受精胚、山羊同种克隆胚和羊-兔异种克隆胚的囊胚期胚胎染色体分析表明，三种来源的胚胎其染色体数目均为60条，且所有常染色体均为端部着丝点染色体，X染色体为第二大的端部着丝点染色体，说明山羊同种克隆胚和山羊-兔异种克隆胚均为山羊的核型，是供体细胞核在不同胞质中的重新编程的结果。4。

Traditional Cancer chemotherapy is often hampered by an insufficient therapeutic index , lacking of specificity, and the emergence of drug — resistant cell subpopu-lations.

传统的抗肿瘤药物选择性不高，既杀伤肿瘤细胞，也损害体内繁殖旺盛的细胞或某些特定类型的正常细胞，常出现较明显的毒性反应。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。