Today’s SAT question of the day is an identifying sentence error question about one of the most commonly tested subjects in the SAT writing multiple choice sections: verbs!

As you read the sentence, you get some clues about the verbs that relate to Galileo: the telescopes “were”, and we modeled on instruments “built by”…these verbs are in the past and their actions are completed.

When we get to D, then, “having used” doesn’t fit with the time frame of our other Galileo-related events. “To have used” would be the correct phrase here, so D is the correct answer because it’s where we find the error.

Always check your verbs! 🙂