时序电路是指它的输出不仅取决于当时的输入，而且也取决于过去的输入，即过去输入不同，则在当前的情况下，输出也可能不同。-Sequential circuit is the output depends not only on its input at that time, but also on past input, that is different from the last input, then in the current circumstances, the output also may be different.