This is a bloody tractor trailer http://i02.i.aliimg.com/img/pb/939/944/233/1263093063182_hz_myalibaba_web9_358.jpg
and this is semi trailer!!!! http://img.diytrade.com/cdimg/595496/4464177/0/1192282085/Van_Semi-Trailer.jpg
TRACTOR TRAILER DOES NOT MEAN EVERYTHING THATS TOWED IS TRACTOR!!!
this is a truck http://upload.wikimedia.org/wikipedia/commons/1/13/Volvo_bobtail_semi-truck_(LandSpan).jpg
and this is a tractor http://www.comparequotes.net.au/Images/car-transport/transporting%20tractors.jpg
HOW THE FREAKING EFF CAN ANYBODY GET THIS WRONG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!???????