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.
In 1887, the first dry cell battery was invented. Unlike previous batteries, it used a paste electrolyte instead of a liquid. This was the first battery suitable for portable electrical devices, as it did not spill or break easily and worked in any orientation.