could（过去式）、can、be able to 都翻译为“能”,表示先天或后天学到的能力、技能
Could表示过去具备做某事的能力,不表示行动、行为
Was/were able to 表示过去成功的做了某事（已做而且成功）
Couldn’t：表示过去没有能做成某事情（做了不成功）
现在能：can am/is/are able to
将来能：can will/shall be able to
his men were able to take a great many photographs of the mountains that lay below, they soon ran into serous trouble.
lei 处于，below 在....下面，run into trouble是“遇到麻烦”的意思，
The plane was then able to rise and it cleared the mountains by 400 feet.
Clear 通过(文中：飞过)，过海关．用clear，日本好多游戏通关了．也会出来一个clear
