lai qu - come and go hui lai - come back hui qu - go back Since you didn't indicate the 'four tune' of the these words（acutlly they are 'ping ying' like phonetic symbol of Enlish）,maybe these answers are incorrect.Hope can help you!

i m gonna give u some examples: lai qu-ta zong shi lai lai qu qu de. He;s always come then leave. hui lai- wo hui lai le I'm back hui qu-wo yao hui qu le I gotta go home./back

Durk's answer is right, and it seem that the tones are lai2 qu4=come and go hui2 lai2=come back hui2 qu4= go back It seems Theresa is a beginner of learning Chinese. When you are learning Chinese you should focus on the tones,because the same pinyin with different tones have differnt meaning. And tones are difficult for foreigners, if you can master it at the beginning, it won't be a headache for your following study.