Fill in the given words to complete the sentences

1. After walking in the freezing rain, her feet were as ... as ice.
2. Jack is not a very compassionate person; he's as ... as nails.
3. The leaves are as ... as a bone and break into powder when you touch them.
4. The water in the ocean is as ... as crystal.
5. We could hardly see anything in the cave, we were as ... as bats.
6. When the pickpocket stole her wallet; he was as ... as lightning.