Ⅰ. 用方框内所给词的正确形式填空
seriously, merry, swallow, decoration, envelope
1. Our maths teacher is careful and takes everything _________.
2. The hungry boy _________the bread without a drop of water.
3. Check the address on the _________before you send it.
4. Make sure all the _________of the hall are OK before you leave.
5. The birds were singing _________at the top of the tree.
