对于区分 can 和 can't 有困难的人士,曾经有个建议说 用be able to和be unable to来代替。我也曾经这样说过。7 C% d3 B7 M% j- ^4 g
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但是要分场合。因为be able to实际的含义是有能力做。要是忽视这个含义,就可能出错。1 j* e" ~" _3 P3 m' r# L' h
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比如,The rules can't be enforced. 要是给换一下,变成了 The rules are unable to be enforced. 这句话在逻辑上乱七八糟。因为rules本身没有什么能力去被执行。如果说 The manager was unable to enforce the rules. 逻辑上语法上都说得过去,可是被迫使用了主动语态,与原意不完全符合。2 `8 A% @: H8 u7 w# a/ u7 @/ t
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下面是一个老外在网上出售仿真枪时作的说明: 6 L& j( I* Z3 `7 f o0 ^1 x6 m- H. ]! O
This item cannot be made to fire and has never been capable of firing. The metal is not strong enough to hold a charge. For decorative purposes only. & s C* b2 A6 d2 G' ]' K
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谨供参考。