以下是三篇关于开学第一天的英语作文范文，均符合100字要求：
范文一
Today is the first day of school, and I was so excited to see my friends and teacher again. Our classroom looked bright and colorful, filled with new energy. I met my best friend, who is taller than before, and we chatted happily. Our teacher is as strict as before, but we are all eager to learn. I hope to do better this term and make new friends together。
范文二
Our school is much more beautiful than before. The grass in front of the office building is so green, and the river beside it is so clean. I bring my new backpack and go to school happily. When I walk into the new classroom, I see all my classmates looking excited. I wish to learn and grow together in the next three years。
范文三
The first day of high school life is full of excitement and challenges. I feel a bit nervous about meeting new teachers and classmates, but I am also eager to start this new journey. I hope to make new friends and share the joy of learning. I know there will be difficulties, but I believe we can overcome them together。