Present&past partiples(ed&ing)

"ed" is past tense basically. When you add "ed" to an adjective, it means the event had happened already.
For example, He attended the meeting at 4pm yesteray.


"ing" is a gerund or it can be used to describe events going on currently.
For example, He is performing a CT scan for a patient right now.

2013-06-04 04:15:44 補充：
"ing" can also be used as an adjective. For example, imposing, appealing.

ed describe how a person feels
ing describe the thing or the person that causes a feeling
eg: I am disappointed with my results.
It was a confusing situation.

is ,am , are, was, were + ing
past tens +ed