—When do we need to pay the balance?
—________ September 30.
A. In B. By C. During D. Within
—When do we need to pay the balance?
—________ September 30.
A. In B. By C. During D. Within
B
September 30是一个具体的日子，可用on，但用in不对；by“到……为止”；during“在……期间”；within“在……范围内”。由句意知选B。