1.
Online group buying is now extremely popular, with one well-known group buying Web site's revenue jumping from NT$13 million last August to NT$27 million at the end of last year, and an average of more than 700 new groups being established each day.
请问句末的each day为何不加in，变in each day呢？两者有通用吗？
2.
She suggests doing someresearchbefore taking part in a group buy and that the only way to save money smartly is by staying aware of the price of the goods you want to buy.
请问before是因为它是介系词，所有后接动名词taking吗？名词是否也可接于before后方呢？
谢谢各位的解答