[noun] + しか + [verb ない-form] [noun] + [particle] + しか + [verb ない-form] [verb (dictionary form)] + しかない
しか means "only", and it always goes with a negative verb: literally "apart from X, there isn't". It follows the noun it limits, and the verb at the end is in the ない-form or ends in ません.
With an affirmative verb the sentence falls apart.
しか replaces が and を. Other particles stay, and しか comes after them: にしか, でしか, からしか.
After a dictionary-form verb, しかない means "there's nothing to do but", "have no choice but". That use has its own grammar point.