In the 1920s _ pet owners and dog trainers used vocal commands to train dogs. _ Carl Spitz used hand signals to drain dogs. Choices 1st blank: both, first, then 2nd blank: also, second, however

The greatest gift the sumerians gave the world was the invention of writing. the sumerians were wealthy people. they needed some way to keep track of what they owned. they began drawing pictures. they used a reed as a pen. they drew on soft pieces of clay. the soft clay was then dried in the sun. the tablet became a permanent record. later, the sumerian drawings changed into wedge-shaped symbols. this kind of writing is called cuneiform. by putting symbols together, the sumerians could write entire sentences.