平行四边形的周长为50,设它的长为x,宽为y,则y与x的函数关系为( )
A:y=25﹣x
B:y=25+x
C:y=50﹣x
D:y=50+x
△ABC的内角A,B,C所对的边分别为a,b,c,a=80,b=100,A=30°,则此三角形( )
Please ______ some vegetables to me when you come here next time.