问题
选择题
I had been working on math for the whole afternoon and the numbers ________ before my eyes.
A．swim
B．swam
C．swimming
D．had swum
答案
B
题目分析：句意：我一整个下午都在做数学题，那些数字在我的眼前转。主句用过去完成进行时，所以后半句用一般过去时，只有这样才能具备“过去的过去”的条件。选B。
