牛津實用英語語法:312 could用于間接引語
A could表示能力
1 could表示目前的能力時在間接引語中保持不變：
I cant/couldnt stand on my head，he said.
他說：我不能做三點倒立。相當于：
He said he couldnt stand on his head.
他說他不能做三點倒立。
2 could表示將來的能力時，在間接引語中可以保持不變，或由would be able結構來轉述：
He said，I could do it tomorrow.
他說：我明天能做這事。相當于：
He said he could do it/would be able to do it the next day.
他說他第二天能做這事。
3 條件句類型2中，主句中的could與A2中的變化相同：
If I had the tools I could mend it，he said.
他說：如果我有工具的話，我就能修補它。相當于：
He said that if he had the tools he could/would be able to mend it.
他說如果他有工具的話，他就能修補它。
would be able在這里暗指所假設的情況有可能實現(可能他可以借到工具。)
4 條件句類型3中，could被轉述時保持不變。
5 could表示過去的能力時，在間接引語里保持不變，或用had been able結構轉述：
I could read when I was three!she boasted.
她吹噓說：我三歲時就能看書了!相當于：
She boasted that she could/had been able to read when she was three.
她吹噓說她三歲時就能看書了。
B could表示允許
1 條件句類型2中的could在間接引語中可保持不變，或由would be allowed to轉述：
If I paid my fine I could walk out of prison today，he said.
他說：如果我交了罰款，我今天就能走出牢門了。相當于：
He said that if he paid his fine he could/would be allowed to walk
他說如果他交了罰款他會被允許走
2 表示過去時態的could在間接引語中可保持不變，或用 was/were allowed to或had been allowed to結構來轉述：
He said，When I was a boy I could stay up as long as I liked.
他說：我小時候，我可以想呆到多晚睡覺就呆到多晚。相當于：
He said that when he was a boy he could/was allowed to stay up./He said that as a boy he was/had been allowed etc.
他說他小時候，可以/被允許愛呆到多晚睡覺就呆到多晚。
A could表示能力
1 could表示目前的能力時在間接引語中保持不變：
I cant/couldnt stand on my head，he said.
他說：我不能做三點倒立。相當于：
He said he couldnt stand on his head.
他說他不能做三點倒立。
2 could表示將來的能力時，在間接引語中可以保持不變，或由would be able結構來轉述：
He said，I could do it tomorrow.
他說：我明天能做這事。相當于：
He said he could do it/would be able to do it the next day.
他說他第二天能做這事。
3 條件句類型2中，主句中的could與A2中的變化相同：
If I had the tools I could mend it，he said.
他說：如果我有工具的話，我就能修補它。相當于：
He said that if he had the tools he could/would be able to mend it.
他說如果他有工具的話，他就能修補它。
would be able在這里暗指所假設的情況有可能實現(可能他可以借到工具。)
4 條件句類型3中，could被轉述時保持不變。
5 could表示過去的能力時，在間接引語里保持不變，或用had been able結構轉述：
I could read when I was three!she boasted.
她吹噓說：我三歲時就能看書了!相當于：
She boasted that she could/had been able to read when she was three.
她吹噓說她三歲時就能看書了。
B could表示允許
1 條件句類型2中的could在間接引語中可保持不變，或由would be allowed to轉述：
If I paid my fine I could walk out of prison today，he said.
他說：如果我交了罰款，我今天就能走出牢門了。相當于：
He said that if he paid his fine he could/would be allowed to walk
他說如果他交了罰款他會被允許走
2 表示過去時態的could在間接引語中可保持不變，或用 was/were allowed to或had been allowed to結構來轉述：
He said，When I was a boy I could stay up as long as I liked.
他說：我小時候，我可以想呆到多晚睡覺就呆到多晚。相當于：
He said that when he was a boy he could/was allowed to stay up./He said that as a boy he was/had been allowed etc.
他說他小時候，可以/被允許愛呆到多晚睡覺就呆到多晚。
