Hiện tại hoàn thành và quá khứ đơn 1. We....... another country before. (not/go) 2. I'am sorry, but I ............. my homework. (not/do) 3. ............. the game of chess? (play) 4. The girls ............. their lunch yet. (not/have) 5. I............ my keys, so I can't open that door. (lose) 6. Columbus............... in the New world in 1492. (arrive)