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。 + F: a0 g. G0 l7 F" } B7 `$ P6 `! |; Z# E5 Z9 Q. _# a, R
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。. @. z* m& b7 X6 R( i
. A$ z& e) E& B8 F# Y* g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。' [; `' U; d- c+ x6 g D9 v% R
5 A- S5 b$ m9 p+ k下面是一个老外在网上出售仿真枪时作的说明: 4 X& P* w6 T) B; u! b. h P+ C# v& T7 l* B' p8 D
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- J' A0 U/ C- U3 o