1、It is October 1st today.
否定句：It is not October 1st today.一般疑问句：Is it October 1st today?
(过去式,补yesterday）否定句：It was not October 1st yesterday.
(过去式,补 yesterday）一般疑问句：Was it October 1st yesterday?
提问：What's the date today?
(过去式,补 yesterday）提问：What was the date yesterday?
2、She wrote a letter in her office yesterday.
否定句：She didn't write a letter in her office yesterday.
一般疑问句:Did she write a letter in her office yesterday?
(一般现在时,补often）否定句：She doesn't often write a letter in her office .
(一般现在时,补often）一般疑问句：Does she often write a letter in her office
（原句提问wrote a letter）：What did she do in her office yesterday?
(一般现在时,补often）提问：What does she often do in her office
（She often writes a letter in her office .对：writes a letter提问）