1、Could you please help me?

你能帮助我吗？

2、I couldnt come over to give you a hand.

我不能过来帮助你。

3、A：——There is a man.Could it be Tom?

那儿有个男子。可能是汤姆吗？

B：——It couldnt be Tom .He has gone to Beijing yesterday.

不可能是汤姆。他昨天已经去北京了。

4、Jack said he could finish the work all by himeself.

杰克说，他靠自己完全能够完成这项工作。

5、He could have completed the project on time then if he made all efforts.

如果他全力以赴的话，他当时本来萌购按时完成这项工程的。