A、 It is the largest supplier of valuable minerals.
B、 It will disappear in about thirty years.
C、 It is beginning to grow smaller and smaller.
D、 It offers many resources to help mankind survive.

【正确答案】 D

【答案解析】解析：短文提到在技术发达的现代世界里，海洋可以提供许多资源以帮助人类生存下去，故D为答案。

A、 Iron and copper.
B、 Gold and copper.
C、 Nickel and bronze.
D、 Iron and bronze.

【正确答案】 A

【答案解析】解析：短文提到海床上有很多有价值的矿物质，such as后又以铁、铜作为例子，故选A。

A、 The sea level will be 20 centimeters higher than it is now.
B、 The sea will be empty if we continue fishing at this pace.
C、 The problems to explore the sea will have been largely solved.
D、 People will depend largely on sea foods and minerals.

【正确答案】 C

【答案解析】解析：短文结尾处提到2050年，对海洋资源的开采问题在很大程度上将得以解决，故选C。