An unsupervised flower shop operated by a college student in Beijing is attracting many young customers, Chinese media reported.

Different from traditional shops in the capital, the young storekeeper surnamed Wang opened the first unsupervized flower shop where people can select flowers and pay via mobile payment systems including WeChat and Alipay.

Born after 1995 and a lover of fiction, the young man said he ____began____(begin) the startup because it will not take up his time. "People go to flower shops at any time," he said. "I cannot focus on reading when I have to serve customers." So Wang opened the self-service flower shop after doing market research.

为什么这里答案是began呢。个人理解：

因为 said 是过去的事，begin这个startup是said之前的事，完全符合过去的过去啊。

而且宾语从句中时态要注意的问题就是如果主句用过去时的话，从句要用相应的过去时态，如果从句动作发生在主句之前，那么从句就要用过去完成时，完全符合，那么为什么这里填began呢。。求解。