We have been good friends since _______.
A:2 years
B:2 years before
C:we are 14
D:2 years ago
make up one's mind; give in; ever since; be fond of; grow up: on schedule; change one's mind ;care about; prefer to; get sb. interested in
如图,斜靠在墙上的梯子AB,梯脚B距墙面1.6米,梯上一点D距墙面1.4米,BD长0.55米,则梯子AB的长为( )米
若函数fx=x1-2x-x2,则函数fx( )