If 一般过去时陈述句，主句过去完成时虚拟语气， 这种结构怎么样理解呢？

The explanation came a week later. It was about ten o' clock at night; I had been dining by myself at a restaurant, and having returned to my small apartment, was sitting in my parlour, reading I heard the cracked tinkling of the bell, and, going into the corridor, opened the door. Stroeve stood before me.

"Can I come in?" he asked.

In the dimness of the landing I could not see him very well, but there was something in his voice that surprised me. I knew he was of abstemious habit or I should have thought he had been drinking. I led the way into my sitting room and asked him to sit down.

"Thank God I've found you," he said.

"What's the matter?" I asked in astonishment at his vehemence.

I was able now to see him well. As a rule he was neat in his person, but now his clothes were in disorder. He looked suddenly bedraggled. I was convinced he had been drinking, and I smiled. I was on the point of chaffing him on his state.

"I didn't know where to go," he burst out. "I came here earlier, but you weren't in."

"I dined late," I said.

I changed my mind: it was not liquor that had driven him to this obvious desperation. His face, usually so rosy, was now strangely mottled. His hands trembled.

"Has anything happened?" I asked.

"My wife has left me."

He could hardly get the words out. He gave a little gasp, and the tears began to trickle down his round cheeks. I did not know what to say. My first thought was that she had come to the end of her forbearance with his infatuation for Strickland, and, goaded by the latter's cynical behaviour, had insisted that he should be turned out. I knew her capable of temper, for all the calmness of her manner; and if Stroeve still refused, she might easily have flung out of the studio with vows never to return. But the little man was so distressed that I could not smile.

上面节选中，I knew her capable of temper 中 know这个动词，capable of temper 为何可以用作宾补？ know 以前好像没见过如此的宾补。

另外， if Stroeve still refused, she might easily have flung out of the studio...if Stroeve still refused - 这是一般过去时的陈述句（表事实）, 但为何后面 she might easily have flung out of the studio...用了虚拟语气呢？ 这里为何不是

if Stroeve still refused, she might easily fling out of the studio 呢？ 没理解...... 

你读句子，一直脱离语境而孤立的剖析句子结构，这致使你虽然了解某个结构有多种使用方法，却不会判断在具体某个句子中到底是哪种使用方法。你往前倒回去几句话，认真读并理解故事的情景。然后再结合故事的情节进步，理解这个句子： and if Stroeve still refused, she might easily have flung out of the studio with vows never to return. 

if从句是真实条件句，即这个条件可能是事实。说话人不了解是不是拒绝赶某人走，但有这种可能。这句则是陈述语气的情态动词推断性使用方法，推断某件事在过去可能发生了。这里的might have done并非虚拟语气。而是陈述语气。

《牛津》know的使用方法之1、

know somebody/something to be/do something We know her to be honest.

即know可将来接to be+形容词作宾补。当to be+形容词作宾补时，形容词为to be的归属性表语，to be 后接归属性表示时，to be一般都是可以省略的。你的句子中，就是省略了to be. 即 I knew her capable of temper. = I knew her to be capable of temper.