We___such great achievements without your efforta:were unable to makec:couldn't have made
问题描述：
We___such great achievements without your effort
a:were unable to make
c:couldn't have made
答
选c
因为without 有虚拟的意思,如果没有你的努力,我们不可能取得如此大的成功.虚拟句中用完成时