酷热的非洲，几乎没有适于航海的河流，这些河流从内陆高原到海岸平原一路穿瀑布、过险滩，倾流而下。
Few of tropical Africa's rivers are navigable from the ocean, dropping as they do from interior tableland to coastal plains by a series of falls and rapids.
成都市红星路下穿市政隧道首次采用了顶部开孔的自然通风方式。
The first use of urban tunnel with upper vents is HongXing road tunnel in ChengDu.
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