有同学问了一个关于“Its time句型”的问题，如下图所示：
If you have really been studying English for so long, its about time you _____ able to write letters in English.
A. should beB. were C. must be D. are
问：我选了A，错了，答案是B，请问A和B两个选项区别在哪？
答： 请先参考下面例句：
1.Its time that we getback to some core principles that united Republicans in the past.
NPR: Sen. Ensign: Economy Hurt GOP Candidates
2.So I think its time that the people knowwhat theyve been up to.
FORBES: Intelligent Investing
3.So weve heard conflicting evidence, conflicting statements, and its time that we getto the bottom of it.
NPR: Political Corner: Gonzales
你给的例句中从句是真实条件从句，主句应该是真实结果主句，那么正确的答案应该是D。
如果结果主句是虚拟语气，那么条件从句应该改为非真实条件句，那么条件从句就应该用虚拟语气： if you hadreally been studying......，那么较为合适的答案应该选择B。
通过以上分析，我们可以看出It is time这种句型后面既可以接虚拟语气，也可以接真实语气，这点和我们中文是一致的。
如：
1. It is high time that someone giveshim the punishment he deserves!
早该有人给他应得的惩罚了。
2. it is time that we gavethem a chance.
是我们给他们一个机会的时候了。
最后总结， It is time句型既可以表达虚拟，也可以表达真实，用过去形态表达虚拟，用现在形态表达真实。
有哪些被广泛采用的英语学习方法其实是不合理的？你中招了没有？
到底什么是英语思维？如何建立英语思维？看完本文就彻底明白了！
what 和 which 有什么区别？为什么 what 不能引导定语从句？
如何区分used to do和be used to do以及be used to doing？
看图学从句，轻松学会什么是主从句，什么是单复句
