One quick note about the problem about theta roles too: Don’t be concerned that the answers to all of the sentences are almost the same. That’s intended. The (a) sentences are going to generally be all alike, with some differences in whether there is a Theme or a Goal, that sort of thing, and the (b) sentences are also going to be alike.

Also: concerning the difference between Theme and Experiencer. In general, an Experiencer is something that is conscious, able to experience something. So, a rock is not a likely Experiencer (though it is a fine Theme). Experiencers are also just about always subjects, like Agents are. Experiencers and Agents basically occupy the same places in sentences.

Themes and Experiencers are both things that the event “happens to” in a certain sense, so they are a little bit difficult to distinguish, but in general just keep in mind that objects are quite likely to be Themes, and subjects are good candidates for Experiencers. (This isn’t a perfect rule, since it doesn’t work with passive sentences, and it is certainly possible for a conscious being to be a Theme, but it’s kind of a workable “rule of thumb.” For this homework, at least, it works.)