The structural safety class is second class, design working life is 50 years.

建筑结构安全等级二级，设计使用年限为50年。

youdao

The safety class of building structure of this project is II and the design working life is 50 years.

本工程建筑结构安全等级为二级，设计使用年限为50年。

youdao

The basic principle, usage of air blowing based level detection, and the structure and application of UCA (h) type nuclear safety class air blowing device are described briefly.

简述吹气法检测液位的基本原理、用途以及UCA (H)系列核安全级吹气装置的结构和应用。

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Around 31% of all students walk or bike to school (as opposed to the national average of 13%), and the public schools give a 12-week-long bike-safety class.

BBC: Living in: Great cities for public transport

Brian Vincent, a former schoolteacher who owns a gun shop in the centre of Gretna and teaches a gun-safety class, says the argument that guns are patently unsafe will not stand up in court.

ECONOMIST: Anti-gun lawsuits (2)

But whatever we can do to reduce bullying and create climates of safety in class, on the way to and from school, at recesses, lunchrooms, we have to do that.

WHITEHOUSE: Press Briefing