I for Shanghai this Saturday, so I want to know when the earliest plane .
A. leave; takes off
B. am leaving; takes off
C. leave; is taking off
D. am leaving; is taking off
网友回答
A. leave; takes off
(答案→)B. am leaving; takes off
C. leave; is taking off
D. am leaving; is taking off
解析：由this Saturday可知应为一般将来时，am leaving 是用进行时的形式表将来时的一种用法，这种用法多是表趋向的动词例如：leave /arrive /e/ go /die等。第二个空飞机什么时候起飞，属于已经制定好的，即为事实，所以用一般现在时。故答案应为B。
句意为：我下周六要去上海，因此，我想知道最早的一班飞机是在什么时候。