requirev.要求;需要;命令;规定
required time工作必要时间
required flow需要流量
required area需要面积
required NPSH所需的净正吸入压头
require nerve需要勇气
required over国外银行本票逾额另须请求字句
require study需要研究
Required Date总司令必需数据
"provided them with all things needful"
"in most schools physical education is compulsory"
"attendance is mandatory"
"required reading"