I usually do my homework but I ______watch TV this evening.这里为什么是might can不行吗

I usually do my homework but I __might____watch TV this evening.
我通常做作业,但今晚我可能会看电视.
这里用might,表示“可能”,是虚拟语气.
用 can行不?行!
I usually do my homework but Ican watch TV this evening. 我通常做作业,但今晚我能看电视了.