To avoid condensation and freeze in the waveguide the nitrogen-gas guideholes and the collection tank are designed.
为了避免波导内部冷凝结霜在波导壁上设计了氮气导孔和氮气收集筒。
2
They stacked rocks with center holes (tube or doughnut shaped) from the surface to the deep stone layer as a guide for their drills (similar to today's guide tubes).
管状或中空管状的中心孔从地表到深石岩石层放满石头,以作为铁转的探头,作用类似今天的导管。
3
The white chalk dust goes through the holes in the paper and marks the wood so the carver has a visual guide to begin cutting.