问题
单项选择题
John insisted that he______everything he could to make sure of Mary’s happiness.
A．do
B．does
C．did
D．must do
答案
参考答案：A
解析： 13．此句中，insist后跟的宾语从句用虚拟语气，即he (should) do everything he could to make sure of Mary’s happiness。