阅读下列对话，选择正确的答案。

Mary: Do you have black bags?

Mr Green: Yes, I do.I have black bags, red bags and blue bags.Do you like these?

Mary: Yes, I do.How much are they?

Mr Green: They are thirty dollars.

Mary: Do you have pants?

Mr Green: Yes, I do.These red pants are seven dollars.

Mary: How much are those pants on the table?

Mr Gteen: Seventeen dollars. And those black pants are twelve dollars.

Mary: I'll take these red pants.

1.They________ white bags.

A. have    

B. don't have

C. aren't

D. are have

2. The bags are________.

A.￥20    

B. $13

C.￥13    

D. $30

3.Mary ________ the bags.

A. like      

B. don't like

C. likes

D. doesn't like

4.The black ________ are $12.

A. bags    

B. shorts

C. pants

D. shoes

5.Which ones are cheap?

A. The red bags.  

B. The blue bags.

C. The red pants.  

D. The black Dants.

某航道上有一桥梁，标注高度15米，已知该地大潮升3.2米，小潮升1.0米，平均海面280厘米，0800潮高0.5米，则当时桥梁的实际高度为（）

A.18.7米

B.17.3米

C.17.7米

D.18.3米