A中 compared to 多余， as....as 就有比较的涵义
B，"A recent..report shows that THERE ARE (more than three times) as MANY HOUSEHOLDS where the children and grandchildren are living in their grandparents' home as THERE ARE HOUSEHOLDS where the grandparents are living in their children's or grandchildren's home."
C: In the past several years, astronomers have detected more than 80 massive planets, most of them at least as large as Jupiter, circling other stars.
因为中间有个插入语 ( , most of them at least as large as Jupiter, )，如果去掉插入语，circling就是紧跟在planets后面修饰planets, 就可以写成astronomers have detected more than 80 massive planets circling other stars
A vs B
谓语+插入语+宾语从句，宾语从句前面的that放在哪里主要取决于插入语修饰的对象，
如果插入语修饰谓语动词，则插入语紧跟谓语动词，that+宾语从句。如we decided, in view of his special circumstances, that we would admit him for a probationary period.
如果插入语修饰宾语，则插入语紧跟宾语从句，谓语动词+that，插入语，宾语从句。如he told her parents that, due to her illness, she would be able to go to school tomorrow.
D.besides做介词+名词，可以做定语也可以做状语，如The cat on the couch loves dogs. on the couch做定语。
E.besides是副词+动词，-ing可以做定语也可以做状语，如The cat sleeping on the rug belongs to Sue.
从词性上无法区分。看and和or的区别。
状语比较的时候，可以省略than后面整个主句，不管时态是否一致。
Eg:
Scientists have gathered evidence suggesting that complex life-forms emerged much earlier than previously thought.
than previously thought (when they emerged)
时间状语的比较，能否省略取决于than前面是否有相应的时间状语。有则than后面主句可以省略；没有则than后面需要补出主谓，以避免比较对象上的歧义。
Eg:
Right: Prices are only 1.3 percent higher this year than last year.
Wrong: Prices are only 1.3 percent higher this year than last year's.
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薛洋
A中 compared to 多余， as....as 就有比较的涵义
B，"A recent..report shows that THERE ARE (more than three times) as MANY HOUSEHOLDS where the children and grandchildren are living in their grandparents' home as THERE ARE HOUSEHOLDS where the grandparents are living in their children's or grandchildren's home."