补全对话。
根据对话内容填入所缺单词，使对话意思完整，每空只填一词。
A: Good afternoon. Tom.
B: Good afternoon, Lucy. Nice see you here.
A: I to this neighbourhood last Monday.
B: to my neighbourhood.
A: Thank you. the way, I want to some food for supper. Where is the grocery shop?
B: Go this road. When you to the main street, turn right. And turn right . You will see
a blue building on the left. It's the grocery shop. It's to find.
A: Thank you very much.
B: Not all.
)，f具有二阶连续偏导数，则
=______．