'Exert' means to apply force on influence over something else, this can be in a negative or positive way. In this quotation, it means that language, if used correctly, has the ability to express a 'hidden power'. It's also worth mentioning that the simile is relevant as the moon has an influence on the level of tides on Earth.
Voting, Polls etc. The most common question type is Multiple Choice, in which participants can choose between several options that you provide. You probably already know much about this type of question, since it has been widely used for surveys.
Multiple Choice is suitable when you already know what options you want the participants to vote on, i.e. you want your audience to choose only from a few pre-defined options.
