直线y=-x+3与两坐标轴所围成的三角形面积为( )。
Ben was busy taking a training class ______ we had to wait for himfor half an hour. [ ]
A. so
B. if
C. or
D. but
“春风不度玉门关”描述的景观位于我国的[ ]
A、西北地区
B、北方地区
C、南方地区
D、青藏地区