....第一句..Children can learn to swim much earlier than is com

....
第一句..
Children can learn to swim much earlier than is commonly supposed..
请问这句是不是在than后面省略了什么...
第二句...
There was a hole in his hat..It had been made when someone fired a shot through his office window.
为什么had been made 在 when 之前呢?不是开了枪..才造成的吗?
it was made when someone had fired...不是这样才对吗?

第一句
省略了”them ,所以翻译过来应该是“孩子们学习游泳往往比他们想象的要简单”
第二句
这儿应该用过去完成时,这件事是过去发生的,从“was那儿就可以看出来,已经发生了,所以是过去完成时,而这个时态的句型结构是had+过去分词,而这儿又是被动,所以用be+done,有因为 be前面是had ,所以用been+done ,关于when和had been done的位置顺序是结构问题
比如 The glass had been smash when I came home.翻译过来就是这个杯子在我回来的时候就打碎了.
再问： 您的例句我倒看得明白...但是 It had been made when someone fired ...怎么还没开枪就已经发生了呢??? had been made 是过去的过去嘛.... fired 是过去...
再答： 在那人射击 时造成的洞，两个动作同时发生，不要把“when....后面的与这个时态联系起来，其实说白咯，when以及when后面的就只是表示时间，就像“since....这种，莫必要在这个时间上纠缠，主要你要把句子的时态以及时态句型搞懂就行咯。不用说敬语，我也不是老师，是学生而已。