我很困惑，什么情况下可以在help后省略to？什么情况下不能省略？
OG-SC中有两个句子，一个是省略了to的，一个是没有省略的。有什么区别吗？
236. The Coast Guard is conducting tests to see whether pigeons can be trained to help find survivors of wrecks at sea.
216. Many policy experts say that shifting a portion of health-benefit costs back to the workers not only helps to control the employer's costs, but also helps to limit medical spending by making patients more careful consumers. | 
