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look out for当心…,留神…,提防…
例句：We were taught to look out for Bad drivers.
我们被教导要当心恶劣的司机。
Look out for a sign to the motorway.
留意通往高速公路的路标。
2.Elders told a BBC correspondent that old feuds were surfacing again because of a lack of arable land and water.
surface在这里是比较形象的用法，表示死灰复燃，浮出水面
3.Hundreds of thousands of people have packed into Revolution Square in the Cuban capital Havana for an international concert aimed at promoting reconciliation between the communist island and its opponents.
pack into装进,挤进,涌入…
例句：These clothes won't all pack into one suitcase.
这些衣物一个箱子装不下。
aim at旨在,目的在于
例句：This book is aimed primarily at computer science.
本书论述的主要是计算机科学。
The factory must aim at increasing production.
工厂应致力于增加生产。
4.He's backed up by 14 other groups from Latin America, Spain and Cuba itself who was expected to be the largest concert ever held on the island.
back up支持
例句：I am always backing you up.
我每次都支持你！
Harris will back me up wholeheartedly as he used to.
哈里斯会像过去一样全心全意地支持我。