1.my friend often (finish)......her homework before she (go) ...to school
2.if we go on (litter) ...., The environment (become).....seriously polluted
3.this is the first time mary....(be) to việt nam
4.l can go to home because it(rain) ......now
5.there thousand cars (produce).........next year
6.my aunt (just/ buy)......a lot of things for tết