分类：教育/科学-学习帮助
问题：英语中虚词用法，具体的句式应该怎么样，好象就这个很容易混淆 
中虚词用法，具体的句式应该怎么样，好象就这个很容易混淆
回答：If的虚拟        
1.现在时 (从句)did/were (主句)would/could/should/might do
2.过去时 (从句)had done    (主句)  would/could/should/might have done
3.将来时(从句)were to do/did/should do  (主句)would/could/should/might do