In this paper, a discrete stage - structured epidemical model is proposed and studied.本文主要讨论了离散的阶段结构传染病模型.OBJECTIVE To explore the administration measures of air condition usage in SARS epidemical period.目的研究传染性非典型肺炎流行期间...
他仍在从事促进当地创业的志愿者工作。He is still involved in voluntary work promoting local enterprise.目前可能正是创业的最佳时机。Now is probably as good a time as any to start a business.他要等到立功、创业的时机成熟时才醒来.He will rest there until the time is ripe for...
查理出生于勃艮第, 是奥地利 、 勃艮第和西班牙三个朝代的产物.Born in Burgundy, Charles was the product of three dynasties: Austria, Burgundy and Spain.他的朝代也因击退了一次孟加拉人大规模的进攻而出名.His reign is also notable for the defeat of a great Bengali raid.我总记不住哪个朝...