Seem is a verb Seeming is an adjective Seem means to appear to be you seem angry today! Seeming is used when appearing something is not true. She said with seeming shy , that she would have to annul the contract.

这个我觉得老外也不一定说得上来，很可能他们会说，都可以，但to be...用得更多。 其实应该是，seem V-ing是seem (to be) V-ing的省略，而且，现在越来越倾向于说 seem to be 我想应该是这样的吧，希望能帮到你~