Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 比尔在尝试参加拳击队之前进行了举重训练。他拿了两个2加仑的瓶子，用沙子装满了它们的70%。如果沙子的密度是5磅/加仑，比尔的这些临时哑铃重多少磅？


### Response:
 首先计算出一个瓶子中沙子的体积：2加仑 * 70% = <<2*70*.01=1.4>>1.4加仑
然后将两个瓶子的重量加倍：1.4加仑 * 5磅/加仑 * 2 = <<1.4*5*2=14>>14磅