人办理续住时，前台应按以下标准操作：与客人确认续住天数→查询流量并加收预付款，输入PMS系统入账→打印《预收款收据》→修改房卡钥匙入住日期；（）→双手递交房卡和《预收款收据》红联→礼貌道别。

________there are a large number of chemical factories, the air is likely to be polluted.

A．Where

B．That　　　　

C．Though

D．As