but for一定要与虚拟语气连用吗

假若but for表示if it were not for或if it had not been for这样的意思（即表示“若不是”“要不是”），它一定要与虚拟语气连用。如：

But for his pension, he would starve. 要不是他有养老金，他就挨饿了。

But for the storm, we should have arrived earlier. 要不是碰到暴雨，我们还会早些到。

But for your help we couldn’thave succeeded in the experiment. 如果没有你的帮助，我们的实验是不会成功的。

如果but for不是表示if it were not for或if it had not been for这样的意思，而是构成not for…but for…这样的搭配，或其中的but只是一个普通的转折连词，其后的for也只是一个普通的介词，此时显然不必与虚拟语气连用。如：

I’m not afraid for me, but for the baby. 我不是为我担心，而是为宝宝担心。

We don’t usually accept checks, but for you we’ll make an exception. 我们通常接受支票，但对你我们可以破例。

The sale was supposed to last for a week, but for all practical purposes it’s over. 减价销售原来预料要持续一周，然而实际上现在已经结束了。

You’ll have your own office soon but for the time being you’ll have to share one. 你很快就有自己的办公室了，不过暂时还得和别人合用一间。