问题
选择题
Only when the European countries’ financial system broke down_____ to take measures to deal with those problems.
A．did they decide
B．they decided
C．they had decided
D．had they decided
答案
答案：A
考查倒装句。only+when引导的状语从句提前，主谓应部分倒装。排除B、C; 有根据broken down，可知应用过去时，故答案为A。