5，Even if two of these were flooded, she would still be able to float.

be able to 强调有能力
ability 能力n.
the ability to do sth.有能力做某事新概念英语第二册1

be capable of doing sth. 强调有做某事的能力
capability of doing sth. 做某事的能力
6，The tragic sinking of this great liner will always be remembered, for she went down on her first voyage with heavy loss of life.

be remembered 被永远记住
go down: sink

on her first voyage 处女航， 首航
with heavy loss of life 损失惨重，造成大批人员的死亡
7, Four days after setting out, while the Titanic was sailing across the icy waters of the North Atlantic, a huge iceberg was suddenly spotted by a look-out.

four days after setting out... : four days after setting off...

icy waters 水域，海域