问题补充：
Mr. Black for Shanghai in a few days. Do you know when the earliest plane on Sunday.
A. leaves; takes off
B. is leaving; takes off
C. is leaving; is taking off
D. leaves; is taking off
答案：
A. leaves; takes off
(答案→)B. is leaving; takes off
C. is leaving; is taking off
D. leaves; is taking off
解析：考查将来时的不同表达法。一般现在时代替将来时指按照时间表安排好要发生的事情；现在进行时代替将来时指代按照事先的安排要发生的事情。句意：Mr Black几天以后要去上海。你知道星期天最早的飞机什么时候起飞吗？第一句用进行时代替将来时指事先安排好的事情。第二句用现在时代替将来时指按照时间表要发生的事情。故B正确。
