英语有个问题看不懂,请指教Though it may be difficult to imagine from a la

英语有个问题看不懂,请指教
Though it may be difficult to imagine from a later perspective,a strain of critical opinion in the
1920s predicted that sound film would be a technical novelty that would soon fade from sight,just as
had many previous attempts,dating well back before the First World War,to link images with
recorded sound.These critics were making a common assumption—that the technological
inadequacies of earlier efforts (poor synchronization,weak sound amplification,fragile sound
recordings) would invariably occur again.To be sure,their evaluation of the technical flaws in 1920s
sound experiments was not so far off the mark,yet they neglected to take into account important
new forces in the motion picture field that,in a sense,would not take no for an answer.
首先 我问的是 as just had many attemps ,我想问的是 just as 的用法是什么?
为什么后面可以接上一个 had （过去分词形式）
just as 后面一般接什么?
然后 我 不懂得是 not so far off the mark
最后 that,in a sense,would not take no for an answer.
that 在这里引导的是什么从句,修饰前面句子的什么部分