NO.PZ2018101901000055
问题如下：
A trader observes that the 50-day moving average for the S&P 500 Index recently crossed below its long-term 200-day moving average. This situation is referred to as a:
选项：
A. death cross.
B. golden cross.
C. Bollinger Band.
解释：
A is correct.
A widely followed moving average crossover signal is the one that takes place between the 50-day moving average and the 200-day moving average. When the short-term (50-day) moving average crosses below the long-term (200-day) moving average, it is called a death cross and is a bearish signal.
麻烦老师截个图，解释下哈
