写出同时满足下列两个条件的数a：a2=16，-a＞0；a=______．
∵-a＞0，
∴a＜0，
∵a2=16，
∴a=-4．
故答案为：-4．
产地和报关地不一致的出境货物：报关地的《出境货物通关单》，产地检疫机构地《出境货物换证凭证》(正本)。( )
An internet is a combination of networks connected by (1). When a datagram goes from a source to a (2), it will probably pass many (3) until it reaches the router attached to the destination network. A router receives a (4) from a network and passes it to another network. A router is usually attached to several networks. When it receives a packet, to which network should it pass the packet? The decision is based on optimization: Which of the available (5) is the optimum pathway?
空白（2）处应选择（）
A.user
B.host
C.city
D.destination
