购买新电器之前，先和有这个电器的人谈谈。
Before you buy a new appliance, talk to someone who owns one.
在克服石头的物理限制和创造新的建筑形式之前，必须先完成结构上的创造。
A structural invention had to be made before the physical limitations of stone could be overcome and new architectural forms could be created.
在你使用新仪器前，你必须先熟悉它。
Familiarise yourself with the new equipment before you attend to use it.
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