heavy traffic还是crowded traffic

heavy traffic还是crowded traffic
 
汉语说“交通拥挤”，说成英语是heavy traffic，还是crowded traffic? 请看题：
“Why couldn’t they meet us at five o’clock?” “Because they were delayed by ________.”http://yingyu.chazidian.com
A. heavy traffic               　                        B. heavy traffics
C. crowded traffic                                      D. crowded traffics
【陷阱】B、C、D三项均容易误选。
【分析】对于此题，首先要明确traffic为不可数名词，没有复数形式，故排除B和D。另外，汉语习惯说“交通拥挤”，而英语习惯上却不能用crowded 来修饰 traffic，要表示汉语的“交通拥挤”，英语通常说heavy traffic，即选A。如下面一题也是选A：
She is not a competent driver and can’t cope with driving in _______.
A. heavy traffic               　                        B. heavy traffics
C. crowded traffic                                      D. crowded traffics