1.第二个句子补充完整了,应该是Is the college the one that sb.went to last year?(the went打错了)
对比一下第一个：Is the river __that ___flows through the town very long?
the river之前之所以没有加the one 是因为后面有very long.
“这条河,也就是从市中心流过的河,很长吗?”
而第二个翻译成“这个大学就是那个大学吗,也就是某人去年去的那个?”
如果第一个句子要加the one,要这么写：
The river---the one that flows through the town--is very long.
2.是作表语.which指代的是前面的状态“深深地投入工作中”,he was often deeply absorbed in work.
因为which可以指代前面的句子或一件事.个人认为这里用as 也可以,同时还可以表示“正如、正像”之意.
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