Real Life: Vehicles and Transportation (4)

I am one part of a large train system. I am an enclosed box-like structure and I have sliding doors on one or both sides. I am used to carry shipments and products and I do not carry passengers. What am I? ......

I am a small boat that moves because passengers use paddles to row me along various waterways. What am I? ......

I am a boat and I can transport passengers over water using sails. The sails guide me and I am actually powered by these sails and wind. What am I? ......

I am a motorized machine that travels under water. Scientists and armed forces usually use me because I am a submerged water vehicle that can travel under great depths of water. What am I? ......

I am a small, motorized water vehicle that people drive on lakes and oceans. I am powered by an engine and people often use me when they want to travel on waterways at high speeds. What am I? ......

I am a car that is used by police forces. I come equipped with sirens and I have a partition that separates the front seat from the back seat where criminals are kept. What am I? ......

I am a bicycle-type unit that children use before they can ride two-wheel bicycles safely. I have three wheels. What am I? ......

I am a motorized vehicle and I can travel on snow and ice because I have ski-like objects beneath me that easily glide and travel on snow. People use me in colder climates in the winter time. What am I? ......

I am a one-wheeled bicycle that people ride in events and circuses. What am I?. ......

I am a bicycle that people ride on rugged trails and other off-road areas. I have bigger wheels than street bicycles. What am I? ......