A formal contract is signed which is renewable annually.正式签订了每年可续签的合同。Seven million doses of vaccine are annually given to British children.英国孩子每年要接种7百万剂疫苗。El Salvador produces 100,000 tons of refined copper annually.萨尔瓦...
And a high molecular weight poly ( arylene ether nitrile sulfone ) has obtained.获得了高分子量的 聚芳醚 腈砜.BUNa - N is a general purpose oil resistant polymer known as nitrile rubber.丁腈橡胶(BUNa-N )是一种多用途抗油品腐蚀聚合物,称为腈橡胶.Organic cyanid...