若直线y=3x+b与两坐标轴围成的三角形面积为6，则b的值为[ ]
A.6
B.-6
C.±3
D.±6
答案：D
图中反映的历史信息正确的是
A．日本兵不堪一击
B．中国儿童抗战威力大
C．抗战的全民性
D．日本投降场面
His shop was so well managed that he sold in just 5 months ________ his competitor sold in a year.
A．how
B．what
C．whether
D．why
