The Beijing Zoo, for one, has opened a much larger elephant enclosure and replaced the concrete in its otter exhibit with natural materials and waterfalls.
北京动物园有建造一个很大的大象围场，取代用混凝土修筑，在里面还有水濑在自然的环境和人造瀑布下表演。
2
For the natural convection in enclosure under permanent magnetic gradient field, the way to generate different magnetic accelerations by different magnetic field arrangements is developed.
针对永磁梯度磁场作用下封闭腔内的自然对流换热，提出通过不同磁场布置产生不同磁加速度的方法。
3
A place, especially an indoor enclosure, for keeping and raising living animals and plants under natural conditions for observation or research.