介绍： Open-source spying does have its risks, of course, since it can be difficult to tell good information from bad. That's where Stratford earns its keep.
译文：公开来源的谍报活动也的确有风险，因为很难区分正确与错误的信息。而这正是斯特雷福德公司赚钱的地方。
点睛：第一句是一个带原因状语从句的复合句，第二句...

介绍： Open-source spying does have its risks, of course, since it can be difficult to tell good information from bad. That's where Stratford earns its keep.
译文：公开来源的谍报活动也的确有风险，因为很难区分正确与错误的信息。而这正是斯特雷福德公司赚钱的地方。
点睛：第一句是一个带原因状语从句的复合句，第二句是一个带表语从句的复合句。
tell在句中是“分辨”的意思。
Can you tell the twin sisters apart?
你分得清这对孪生姐妹吗?
to earn one's keep是“挣钱维持生活”的意思，类似于to earn one’s living、to earn one's bread、to earn one's livelihood或to earn/turn an honest penny“以正当的手段凭努力工作挣钱”。
When you earn your keep, you will be able to do many things that your parents cannot afford to let you do now。
当你能挣钱养活自己了，你就可以做许多你的父母现在负担不起你做的事。