Riddles谜语猜一猜

猜謎是一种很好的锻炼思维的方式。同学们，快叫上你的爸爸妈妈或好朋友，大家一起来猜谜语，看谁先猜出来哦！

1. What are full when they are used（使用） and empty when they are at rest（休息）？

2. What always has one eye open but cant see？

Hint：They protect（保护） your feet from being hurt（受伤）.

Hint：It is made of（由……制成） metal（金属）.

3. We see it once in a year， twice in a week， and never in a day. What is it？

4. What gets larger， the more you take away（拿走）？

Hint：A letter.

Hint：Some animals live there.