—Eric, _____ you talk about the history of China's space programme?
—Sure. Let me show you some photos first.
A:must
B:need
C:may
D:can
煤矿工人在井下作业完毕后乘坐矿井里的升降机返回地面:
若3x2a+3﹣9>6是关于x的一元一次不等式,则a=____.