— Where are _____?

—They are on the chair.

I think the ______ (four) lesson is the most difficult in this book.

Thisbookisthelightestand______(thin)ofallthebooks.

书面表达。

以一种文具为题按要求写一篇英语小作文。

要求：1.要写出此文具的主要特点。

2.条理清楚，意思连贯，标点正确，书写规范。

3.不少于50个单词。

This book is the lightest and ______ (thin) of all the books.