看看下面的句子,你就懂了;
1 If he had worked hard 30 years ago,he would have become very rich.
(这一句讲的都是过去的事情,与“现在”没有联系)------这叫单一虚拟语气句子
==He didn't work hard 30 years ago,so he didn't become very rich.
2 If he had worked hard 30 years ago,he would be very rich today
（这一句叫多重虚拟语气句,因为它含有两种不同的虚拟语气.他过去没有努力赚钱,所以他今天不富有.------“过去”与“现在”互相联系着.）
=== He isn't very rich taday because he didn't work hard 30 years ago.
你的句子也是这个原理：
If the flower had been watered,it wouldn't be daed as it is now.
== The flower is dead now because it wasn't watered.
明白了吗?