1. This box is made of_________ (金属).
2. — What is the _________ (长度)of this road?
    — It's about 168 kilometers.
3. My best friend's __________ (微笑的) eyes make her look cheerful and friendly.
4. I hope I can __________ (收得到)your letter soon.
5. __________ students learn to cook and sew in a Home Economics class.