The platforms extend to a depth of over 100 feet under the sea. These alone took sixteen months to build. Above the surface of the water, the towers rise to a height of nearly 700 feet. They support the cables from which the bridge has been suspended.

　　9. The platforms extend to a depth of over 100 feet under the sea.

　　平台深入海底100英尺。

　　语言点:句子结构分析:of over 100 feet under the sea是depth的后置定语。

　　10. These alone took sixteen months to build.

　　仅这两座塔就花了16个月才建成。

　　语言点1:alone在此处是副词，意为“仅，单单”

　　语言点2:take some time to do sth.的意思是“花费多少时间做某事”。

　　11. Above the surface of the water, the towers rise to a height of nearly 700 feet.

　　塔身高出水面将近700英尺。

　　语言点:句子结构分析:above the surface of the water放在句首，充当地点状语。

　　12. They support the cables from which the bridge has been suspended.

　　高塔支撑着钢缆，而钢缆又悬吊着大桥。

　　语言点:句子结构分析:which引导定语从句，修饰cables。From与从句中的has been suspended形成固定搭配，即suspend from，意思是“从…悬吊下来”。