It is a complexsystem, but it certainly makes a change.
这是个复杂系统，但肯定有所改进。
《柯林斯英汉双解大词典》
2
This is accomplished by a complexsystem of chemical messengers that in plants include hormones and other regulatory molecules.
这是通过一个复杂的化学信使系统来完成的，在植物中包括激素和其他调节分子。
3
It's a complexsystem wherein data is copied to multiple intermediate devices, usually to speed up access to files when millions of people are trying to access the service at the same time.