What is today's assignment in history?关于所有格缩写
问题描述：
What is today's assignment in history?关于所有格缩写
What is today's assignment in history?此句中的what is 为什么不缩写成"What's"?
另外有无规定在什么情况下不能缩写的?
答
一般书面语不用缩写形式,what's 改写成what is;
can't 改写成cannot等等.