受美国金融风暴和世界经济衰退的影响，我国沿海许多出口企业经营发展遇到异常困难。对此，出口企业应该

我国的第一大油田是（    ）。

已知两种离子A²⁺和B^2﹣的核外电子数相同，其中A原子的质子数为a，求B原子的质子数．

阅读下文，回答问题
                                                                                                  On the beach
    It is a fine day. A lot of people go to the beach to enjoy sunshine. Some people are swimming like fishes in the sea. On the beach，some young people are playing volleyball.
    Some of them are lying under the coconut trees. And some old people are chatting with each other. What are the children doing? Look! They are making castles with spade and sand. They are having fun。
⑴⑵⑶⑷⑸根据短文内容，判断正误；⑹根据短文内容填空。

The telephone____by Alexander Graham Bell in 1876.

1.