完形填空

Mr. Smith is old. He has taught math in this school 1 thirty years ago. He works hard and he is strict 2 his students.

This term, he began to teach Grade 1. On the first day of school, he told them how to be 3 honest person. Before the class was over, he asked his students to finish Exercise 6 in Lesson 1.

The next morning, Mr. Smith came into the classroom and asked, "Who has finished Exercise 6?" A few students 4 their hands. He shook his head and said, "Open your books and see 5 there's Exercise 6 in Lesson 1." The students had a look at their books and found there wasn't Exercise 6 at all. Their face turned red at once.