光是

光是	guāng shì	solely / just
光	guāng	light; ray (CL:道) / bright; shiny / only; merely / used up; finished / to leave (a part of the body) uncovered
是	shì	to be (followed by substantives only) / correct; right; true / (respectful acknowledgement of a command) very well / (adverb for emphatic assertion)
是	shì	variant of 是