photography can trace its roots to the camera obscura, the optical principles of which were understood as early as the 5th century bc.

the principles of the camera obscura have been known since antiquity.

暗箱的原理自古以来就已经知道了。

the camera obscura was seen as a drawing tool for a clearer and realistic portrayal of objects.

该暗箱被看作是一个绘图工具，为更清楚和现实的写照物体。

carpinteria, ca indian springs school

印第安泉中学

some views on welding technique of stainless steel in crystal grower

单晶炉不锈钢焊接工艺的探讨

technology for measuring obturation of vacuum in the crystal grower

单晶炉真空密闭性能的检验技术

improvement of vacuum and air-charging systems for czochralski crystal grower

直拉单晶炉真空系统和充气系统的改进

usually remembers the punchlines of jokes

通常能记住些笑话

ecowas committee of four on sierra leone ;

西非经共体塞拉利昂问题四国委员会；

ecowas six - month peace plan for sierra leone ;

西非经共体塞拉利昂六个月和平计划；

ecowas european atomic energy community

西欧原子能共同体

the economic community of west african states ( ecowas )

西非国家经济共同体（简称西共体）

introspection on ecowas'peacekeeping mission to liberia

西共体在利比里亚的维和行动反思

seminar on the senitization and training of administrators of ministries of foreign affairs of ecowas and eccas member states on drugs ;

西非经共体和中非经共体各成员国外交部行政人员关于麻醉药品问题的觉悟和训练问题讨论会；

lnc; ecowas mechanism for conflict prevention, resolution, peacekeeping and regional security;

西非经共体预防和解决冲突、维持和平、区域安全机制；

international workshop on the financing mechanisms and development strategies for cultural industries of the ecowas space ;

关于西非经共体区域文化业筹资机制和发展战略的国际讲习班；

a further obstacle to action from ecowas is nigeria.

西非国家经济共同体行动的障碍更多得来自尼日利亚。

guillaume soro told reporters that the message of ecowas leaders is clear and this is mr. gbagbo's last chance.

索罗告诉记者说，西非共同体领导人发出了明确的信息，这是巴博的最后机会。

ecowas has repeatedly threatened force.

ECOWAS再三地威胁要使用武力。

but this makes it hard for the other ecowas members to criticise nigeria.

但是，这使得其他西共体成员很难批评尼日利亚。

ecowas had taken the lead, holding talks with the soldiers and pro-democracy groups since october.

自从去年十月，在西共体的领导下，与军人和民主派举行会谈。