And the traditional preference for boys sometimes leads to selective abortion, causing worries over the imbalance of gender ratio.
想要男孩的传统偏好导致许多人选择堕胎，这就造成了大家担心男女比例的失衡的问题。
Countermeasures: fair use, temperance drug use, develop the risk-benefit ratio, low residue and selective pesticides.
对策：公道用药，节制用药，研制高效低毒，低残留并有选择性的农药。
Selective suitable conditions such as the ratio of reactions, different catalyst and the addition of dehydrater etc are presented. The result which is the yield of product is 82.5%.
选择了合适的原料配比、催化剂、脱水剂用量等反应条件，反应所得到的丙酮酸乙酯收率为82.5%；
Ratio of ethylene to propylene can be regulated through selective hydrogenation, separation and disproportionation. Requirements on some key parameters are pointed out and the reasons are discussed.
通过选择加氢、分离和歧化反应调整乙烯和丙烯产品的结构比例，指出了对部分主要操作参数的控制及要求，并分析了其原因。
Simulations show that the scheme gives a signal-to-noise ratio (SNR) improvement of about 0.4 dB over a frequency-selective fading channel compared with PN sequence padding.
仿真表明，在频率选择性信道下误符号率较PN序列填充方案有0.4dB左右的性能改善。
Simulations show that the scheme gives a signal-to-noise ratio (SNR) improvement of about 0.4 dB over a frequency-selective fading channel compared with PN sequence padding.
仿真表明，在频率选择性信道下误符号率较PN序列填充方案有0.4dB左右的性能改善。
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