That is ruler.

_________do you like best about the Mid-Autumn Festival—I enjoy the delicious mooncakes.

______ my surprise, every student looked at me _________surprise when I cameinto the classroom

In those days, we had no phones, so we had to keep in touch ________ letters often.

Talking about his success, the famous scientist said, “I’ve been lucky _________there are many people who have helped me”.[ ]