一个长方体铝块密度为2.7×103kg/m3，把它分为两块，每块的密度是（ ）

A : Good afternoon. Welcome to our restaurant.
B : Thank you.
A : Here is a table for two. 1_____
B : Thank you. May I have the menu , please?
A: OK. Here it is. (A few minutes later)2_____
B:  Sure. We'll have Beijing Roast Duck and vegetable    soup.
A:  3_____
B : Yes. Two cups of coffee , please.
A : Anything else?
B: 4_____
A : OK. Thank you for your order.
B : ( Forty minutes later) May I have the bill , please?
A:  Let me see.  5_____
B : Here you are.A : Thank you.