1.I developed very slowly and it took nearly two hundred years before Iwas built as an analytical machine by Charles Babbage. before 引导时间状语从句时可以根据语境译为“要过多久/过了多久才.......; 还没......就，还没等......就......;趁，还没来得及” Think well before you decide.三思而后行。 It was some time before we realized the truth. 过了一段时间我们才知道了事实。 It was long/ a long time before I got to sleep again. 很长时间以后我才又睡着了。

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