某火力发电厂建厂几年后，原来附近绿茸茸的苔藓植物不见了，其主要原因是（    ）

由于冬季蔬菜供不应求，价格较高，所以许多菜农主动建大棚生产蔬菜，增加冬季鲜菜的供给。这主要说明（   ）

A：Welcome to our restaurant.
B：Thank you.____
A：OK. Here it is.(A few minutes later)____
B：I'd like a beef hamburger and salad.
A：____
B：Fruit salad.And some drinks,please.What drinks do you have?
A：We have orange juice,coffee and tea.____
A：It is hot milk with sugar and chocolate.It tastes good.
B：Well,I’ll have a try.
A：OK.Wait a minute,please.
(20 minutes later)
B：____ 
A：Let me see.It's 35 yuan.
B：All right.Here's the money.