| 摘要 |
A cover for a greenhouse or glasshouse comprises mutually parallel channels and ridges, as well as glazing bars which are positioned at an angle between each channel and rib. The connections between each pair of elements, comprising a channel and bar and a ridge and bar or two bars lying opposite one another on either side of the ridge, have, with regard to relative rotational movement about a substantially horizontal axis which runs parallel to the longitudinal direction of the channels and/or ridges, substantially the same flexural strength in both one direction of rotation and the other, opposite direction or rotation.
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