比较can 和be able to
[size=6][color=#4169e1][font=宋体, arial]1）can could 表示能力；可能 (过去时用could), [/font][font=宋体, arial]只用于现在式和过去式(could)。be able to可以用于各种时态。[/font]
[font=宋体, arial] They will be able to tell you the news soon. 他很快就能告诉你消息了。[/font]
[font=宋体, arial]2）只用be able to [/font]
[font=宋体, arial] a. 位于助动词后。[/font]
[font=宋体, arial] b. 情态动词后。[/font]
[font=宋体, arial] c. 表示过去某时刻动作时。 [/font]
[font=宋体, arial] d. 用于句首表示条件。[/font]
[font=宋体, arial] e. 表示成功地做了某事时，只能用was/were able to， 不能用could。[/font]
[font=宋体, arial] He was able to flee Europe before the war broke out.[/font]
[font=宋体, arial] = He managed to flee Europe before the war broke out.[/font]
[font=宋体, arial]注意：could不表示时态[/font]
[font=宋体, arial]1）提出委婉的请求，（注意在回答中不可用could）。[/font]
[font=宋体, arial] --- Could I have the television on?[/font]
[font=宋体, arial] --- Yes, you can. / No, you can't.[/font]
[font=宋体, arial]2）在否定，疑问句中表示推测或怀疑。[/font]
[font=宋体, arial] He couldn't be a bad man. [/font]
[font=宋体, arial] 他不大可能是坏人。[/font]
[/color][/size] 嗯嗯，原来是这样 [b]回复 [url=http://bbs.tingroom.com/redirect.php?goto=findpost&pid=742561&ptid=412170]2#[/url] [i]kobe[/i] [/b]
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