I never thought he would be so easily knocked down,I needn't have him left here any longer.

Question

请讲一下would be so easily 和needn't have him left here 的语法结构。

Answer 1

实际上这句话前半句是用虚拟语气形式表达的。表示与预期或希望达到的目的相反。
句子的含义是“我从没想到过他会这么容易被击垮”
would be so easily knocked down 是knock down的被动语态，同时使用了“与现实相反的虚拟语气”的用法，这种用法结构是“主句用动词的一般过去式，从句用would,should+动词原形”

I needn't have him left here any longer.
need用作助动词，后面接动词原形，结构中含有have sb done"结构，意思是让某人作了某事

整个句子译成：
从没想到过他会这么容易被击垮，我没有必要再把他留在这了。

Answer 2

would be是过去将来时，needn't是情态动词的否定，意思是不需要， have him left here是have sb do sth，让某人怎样怎样，这里比较特殊，left用的是被动，表示他被留在这儿。

Answer 3

还原句子应该是he would be knocked down so easily. be knocked down 被打败，被打倒 easily做副词修饰knocked down。
第二句have sb/sth. done sth 找人去做某事（have sth done)或对付这个人
have sb done"
e.g. He has his rival killed. 就是他找人（这里没有说找谁）把他的对手干掉了He will have his clothes washed 他将找人把他的衣服洗了（这里也没有说找谁，它强调衣服被洗了）本回答被网友采纳

Answer 4

我从没想过他会轻易倒下，我不应该把他留在这儿。
应该是 would be knocked down，easily 副词，修饰knock.
have sb done 让某人被。。。