زبان انگلیسی ترجمه و گرامر

please choose the correct  word between "could" and " can" and  " to be able to" 

1- I............pass my examination ten years ago .

2- I ..........go to the country yesterday and had a good time. 

3- He ......... swim very well when he was young . 

4- He ........... swim half way before he collapsed, .