阅读理解

    Hello, my name is John. I have PE, art and English on Tuesday（星期二）. It's my favourite day. I like English. Look, that is my math teacher. He's very kind. His name is Li Hai. I like beef very much, but I don't like apples. I like bananas, too.

小明用图1所示的电路来测量小灯泡的电功率（部分实验器材的规格已标明）．

看图回答问题：

⑴请写出图中字母所代表的国家。A是____ ，B 是____ 。
⑵以B为中心形成的军事集团是____ 。
⑶在同盟国集团中____ （国家），为了自身利益，最终加入协约国作战。
⑷两大军事集团扩军备战带来的后果是导致____ 的爆发。