I found it easy to understand. The last manual exchange in the US was replaced by automatic switching in the 1970’s, so the reason for the letters is still within living memory for some people. I thought that people who’d used the old system would be able to explain the reason for the letters easily.
I found it easy to understand. The last manual exchange in the US was replaced by automatic switching in the 1970’s, so the reason for the letters is still within living memory for some people. I thought that people who’d used the old system would be able to explain the reason for the letters easily.
Valid.