When you are finished, you should be able to: 1  State the role of a helping verb and list some examples. 2  Explain how helping verbs can clarify the verb tense of a sentence. 3  Identify helping verbs in a sentence.
The dry cell battery is one of the most commonly used types, including AA, 9-volt, and watch batteries. Dry cell batteries are different from wet cells because their electrolytes are contained in a low-moisture paste, while a wet cell has electrolytes contained in a liquid, hence the difference in names.
The first battery appeared in 1866, invented by French inventor, George Leclanche. He called it a single fluid electric generating battery. It was a wet cell, made by filling a glass jar with ammonium chloride, manganese dioxide and zinc and then adding a carbon bar for the positive end of the cell.