用金属铝、锌、铁、铜、银、钙填空

（1）用于制干电池外壳的是______

（2）用在香烟内包装的金属是______

（3）导电性仅次于银，在潮湿的空气中表面会发绿的是______

（4）美容镜上镀的一层金属是______

（5）有助于骨骼和牙齿生长的是______

（6）具有磁性可用它制作起重机的是______．

Under one of the following conditions, goods or services may be procured through competitive negotiation in accordance with this Law: ______.

A．where, qualified tender is lacking，or re-invitation fails
B．where the goods or services in question are special in character and can only be procured from a limited number of suppliers
C．where goods or services can be procured from only one supplier
D．where consistency of the items or compatibility of the services procured requires procurement of additional items or services from the same supplier