Machine tools will keep their accuracy ____they are properly

Machine tools will keep their accuracy ____they are properly lubricated at regular periods.
A.provided that B.even though C.until D.unless
which one?Why?

Amanda66 1年前已收到3个回答举报

心绪-随风春芽

共回答了18个问题采纳率：94.4% 举报

当然是A
因为这句话后半句：
".properly lubricated at regular periods."
的意思就是“定期注润滑油”.
后半句是前半句成立所需要的条件.前半句是“机床保持其精确度”.
provided that = 条件是,倘若,如果

1年前

easfore 幼苗

共回答了1个问题举报

choose C
机床将保持其准确性，除非他们适当地定期进行润滑

1年前

雷蒙得幼苗

共回答了67个问题举报

A
provided that = if

1年前

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