To determine whether or not the employee correctly understands the message, the project manager needs to （）.

A.reduce the filtering

B.eliminate barriers

C.obtain feedback

D.use more than one medium

软切换技术对CDMA系统的贡献主要有：（）

A、提高通话质量

B、减低掉话率

C、提高资源利用率

D、增加掉话率