答题库 【2020最新整理国开(电大)人文英语1-3896网上形考机考题库】The number of these families has increased ______ 40 percent in the past ten years.
【2020最新整理国开(电大)人文英语1-3896网上形考机考题库】The number of these families has increased ______ 40 percent in the past ten years.
选择一项：
A. to
B. up
C. by
