S-6:set foot in 进门
A:What luck!
A:真倒霉！
B:What's the matter?
B:怎么了？
A:When I set foot in the classroom, I found that I forgot my textbook. The teacher happened to ask me to read the text in the class.
A：踏进教室的大门，我才发现自己忘了带课本。上课时老师又偏偏叫我读课文。
B:Be careful next time.
B:下次别这么粗心了。
