be backed by

• Managed resources are backed by system memory
  系统内存对托管资源提供支持。
• My mother will be back by 5 o ' clock this afternoon
  今天下点五点以前我妈妈就回来了。
• She went shopping . she ' ll be back by noon
  她去买东西去了。她中午前回来。
• " now , i must be back by half - past four , " she said
  “不过，我点半必须回去， ”她说。
• If i go there with you ， i ' ll be back by seven
  如果我和你一起去，我会在阒右郧盎乩吹摹
• If i go there with you , i ' ll be back by seven
  如果我和你一起去，我会在7点钟以前回来的。
• Now , george , be sure to be back by 8 : 30
  乔治，八点半以前一定要回家。
• Come on , mom , just this one time . i ' ll be back by eleven
  好了，妈，就这次，我在11点会回来的
• I ' ve got to be back by two o ' clock
  两点以前我一定得回去一下不可。