help !!!!!!!!!!!!

lll123

1.in the beginning of the sentence ,i don't know the difference between "In reference to "and "Referring to"

2.Recently implemented"shift-work equation" based on studies of the human sleep cycle have reduced sickness,sleeping on the job, (fatigue among shift workers, and) have raised production efficient in various industries.
a......
c. and fatigue among shift works,while raising

I think 'a' is correct,but why 'c'?

3.Inuits of the bering sea were( in isolation from contact with european longer than) aleuts or inuits of the north  pacific and northern alaska.
a......
b.isolated from contact with europeans longer than
c.isolated from contact with europeans longer than were

why add 'were' after 'than',i confused to  this kind of sentence,please explain

thanks lot

自尊宝

2. 用while与原句要表达的意思有关，在。。的同时，。。。

3。有were才符合compare apples with oranges

mindfree

2. 的问题是原句意思和逻辑关系.四个部分前三个是并列的(sickness, sleeping, and fatigue).

3. 补上were优于没有were,因为避免了歧义.B中的歧义在于:可以理解为Inuits...与European隔离比其与Aleuts或Inuits的隔离时间长.改变句意.