_____ a cold morning, I opened the window and was glad to find that it was snowing outside. [ ]

A. By

B. On

C. In

D. At

经纪类证券公司只能从事特定的业务，即（）

A.证券自营业务

B.证券承销业务

C.证券投资咨询业务

D.证券代理买卖业务