A:x°23+y°22>1
B:x°23+y°22<1
C:3x°2+2y°2>1
D:x°3+y°2<1
已知x无论取何正值,y1=-3x+7都比y2=kx+5大,求k的取值范围.
元素种类由____ 决定,元素化学性质由____ 决定.
Two old men were playing chess in the park with trees ________ shade.