书名：新多益阅读大破解
页数：p.169
题目：
In order to ______ live video in a window, individual video images and
video clips can be digitized and stored to disk.
(A)display
(B)displays
(C)displaying
(D)displayed
答案是C，请问各位多益满分的大大这里为什么不能用A呢？他的解析看不太懂