用括号中所给单词的适当形式填空,使句子完整、通顺.

用括号中所给单词的适当形式填空,使句子完整、通顺.
12.Thanks for ______ (sweep) the floor for me,Tom.
13.It’s too difficult.I can’t finish the work ______(without) your help.
14.We celebrate ______ (nation) Day on October 1 everyyear.
15.A lot of ______ (visit) came to our schoolyesterday.
16.The students are having a ______ (meet) on theplayground.
17.______ (luck),the boy was not badly hurt in theaccident.
18.His parents are still ______ (alive),but he diedtwo years ago.
19.Tina’s father is a computer ______ (program),andhe has a lot of work to do every day.
20.Chinahas built a new Great Wall across the ______ (north) part of the country.