The effectiveness of an air tight ventilatory dust exhaustive system with closed circuit cycle and pulse fissure blow filter bag was studied.
本课题采用的闭路循环式密闭通风除尘系统，使用环隙喷吹脉冲滤袋除尘器。
2
The Filter Hypothesis proposed by Stephen Krashen has important implications both for L2 learners and teachers. However, the explanations given by Krashen are not exhaustive.