He had divined her question and was ready with an answer.
"I've just found out that we're supposed to water our lawns only before seven in the morning or after seven in the evenings. It's the law."
It was the day for their monthly drive out to Wheaton to visit Uncle Fabius. On the whole, Ernie was glad his sister was in the car when he turned the key in the starter—it forced him to be calm and collected, though he didn't feel exactly right about exposing her to the danger of being blown up without first explaining to her the risk. But the motor started right up and began purring powerfully. Ernie's sister commented on it favorably.
Then she went on to ask, "Did you remember to buy gas yesterday?"
"No," he said without thinking; then, realizing his mistake, quickly added, "I'll buy some in Wheaton. There's enough to get us there."
"You didn't think so yesterday," she objected. "You said the tank was nearly empty."
"I was wrong. Look, the gauge shows it's half full."
"But then how ... Ernie, didn't you once tell me the gauge doesn't work?"
"Did I?"