问题如下：
Based on the three economic outlook statements, a profitable long/short trade would be to:
选项：
A.go long a Canadian CDX IG and short a US CDX IG.
B.short an iTraxx Crossover and go long an iTraxx Main.
C.short electric car CDS and go long traditional car CDS.
解释：
B is correct.
Based on Outlook 1, Chan and Smith anticipate that Italy’s economy will weaken. In order to profit from this forecast, one would go short (buy protection) a high-yield Italian CDS (e.g., iTraxx Crossover) index and go long (sell protection) an investment-grade Italian CDS (e.g., iTraxx Main) index.
请问老师这个main和cross的概念在讲义中哪页呢？我怎么一点印象都没有。。
